[PATCH 2/5] sched: Split out kernel/sched/fair_balance.c from kernel/sched/fair.c

[Ingo Molnar]

Move the SMP load-balancing code into the new fair_balance.c file,
because it's mostly self-contained code that comprised about 50% of
the lines of code in fair.c.

Expose the sched_balance_softirq(), sched_balance_find_dst_group(),
cpu_load_without(), cpu_runnable_without(), cpu_util_without(),
sched_balance_newidle(), task_h_load(), throttled_lb_pair(),
task_util(), task_util_est() and a number of other methods
internally to better facilitate this code separation.

Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 kernel/sched/Makefile       |     1 +
 kernel/sched/core.c         |     1 +
 kernel/sched/fair.c         | 10366 +++++++++++++++-----------------------------------------------
 kernel/sched/fair_balance.c |  5103 +++++++++++++++++++++++++++++++
 kernel/sched/sched.h        |   256 ++
 5 files changed, 7909 insertions(+), 7818 deletions(-)

diff --git a/kernel/sched/Makefile b/kernel/sched/Makefile
index c7afe445480a..898f6062a2a7 100644
--- a/kernel/sched/Makefile
+++ b/kernel/sched/Makefile
@@ -31,5 +31,6 @@ endif
 obj-y += core.o
 obj-y += syscalls.o
 obj-y += fair.o
+obj-y += fair_balance.o
 obj-y += build_policy.o
 obj-y += build_utility.o
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7fbb53d27229..013ce552941a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8337,6 +8337,7 @@ void __init sched_init(void)
 	balance_push_set(smp_processor_id(), false);
 #endif
 	init_sched_fair_class();
+	init_sched_fair_class_balance();
 
 	psi_init();
 
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1dd37168da50..9eba1c4e2a00 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -91,31 +91,6 @@ static int __init setup_sched_thermal_decay_shift(char *str)
 }
 __setup("sched_thermal_decay_shift=", setup_sched_thermal_decay_shift);
 
-#ifdef CONFIG_SMP
-/*
- * For asym packing, by default the lower numbered CPU has higher priority.
- */
-int __weak arch_asym_cpu_priority(int cpu)
-{
-	return -cpu;
-}
-
-/*
- * The margin used when comparing utilization with CPU capacity.
- *
- * (default: ~20%)
- */
-#define fits_capacity(cap, max)	((cap) * 1280 < (max) * 1024)
-
-/*
- * The margin used when comparing CPU capacities.
- * is 'cap1' noticeably greater than 'cap2'
- *
- * (default: ~5%)
- */
-#define capacity_greater(cap1, cap2) ((cap1) * 1024 > (cap2) * 1078)
-#endif
-
 #ifdef CONFIG_CFS_BANDWIDTH
 /*
  * Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool
@@ -309,10 +284,6 @@ const struct sched_class fair_sched_class;
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
 
-/* Walk up scheduling entities hierarchy */
-#define for_each_sched_entity(se) \
-		for (; se; se = se->parent)
-
 static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
 {
 	struct rq *rq = rq_of(cfs_rq);
@@ -381,7 +352,7 @@ static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
 	return false;
 }
 
-static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
+void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
 {
 	if (cfs_rq->on_list) {
 		struct rq *rq = rq_of(cfs_rq);
@@ -406,11 +377,6 @@ static inline void assert_list_leaf_cfs_rq(struct rq *rq)
 	SCHED_WARN_ON(rq->tmp_alone_branch != &rq->leaf_cfs_rq_list);
 }
 
-/* Iterate through all leaf cfs_rq's on a runqueue */
-#define for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos)			\
-	list_for_each_entry_safe(cfs_rq, pos, &rq->leaf_cfs_rq_list,	\
-				 leaf_cfs_rq_list)
-
 /* Do the two (enqueued) entities belong to the same group ? */
 static inline struct cfs_rq *
 is_same_group(struct sched_entity *se, struct sched_entity *pse)
@@ -477,25 +443,15 @@ static int se_is_idle(struct sched_entity *se)
 
 #else	/* !CONFIG_FAIR_GROUP_SCHED */
 
-#define for_each_sched_entity(se) \
-		for (; se; se = NULL)
-
 static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
 {
 	return true;
 }
 
-static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
-{
-}
-
 static inline void assert_list_leaf_cfs_rq(struct rq *rq)
 {
 }
 
-#define for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos)	\
-		for (cfs_rq = &rq->cfs, pos = NULL; cfs_rq; cfs_rq = pos)
-
 static inline struct sched_entity *parent_entity(struct sched_entity *se)
 {
 	return NULL;
@@ -1005,8 +961,6 @@ static void update_deadline(struct cfs_rq *cfs_rq, struct sched_entity *se)
 #ifdef CONFIG_SMP
 
 static int select_idle_sibling(struct task_struct *p, int prev_cpu, int cpu);
-static unsigned long task_h_load(struct task_struct *p);
-static unsigned long capacity_of(int cpu);
 
 /* Give new sched_entity start runnable values to heavy its load in infant time */
 void init_entity_runnable_average(struct sched_entity *se)
@@ -1098,9 +1052,6 @@ void init_entity_runnable_average(struct sched_entity *se)
 void post_init_entity_util_avg(struct task_struct *p)
 {
 }
-static void update_tg_load_avg(struct cfs_rq *cfs_rq)
-{
-}
 #endif /* CONFIG_SMP */
 
 static s64 update_curr_se(struct rq *rq, struct sched_entity *curr)
@@ -1305,7 +1256,8 @@ update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
  * Scheduling class queueing methods:
  */
 
-static inline bool is_core_idle(int cpu)
+#ifdef CONFIG_SMP
+bool is_core_idle(int cpu)
 {
 #ifdef CONFIG_SCHED_SMT
 	int sibling;
@@ -1321,12 +1273,12 @@ static inline bool is_core_idle(int cpu)
 
 	return true;
 }
+#endif
 
 #ifdef CONFIG_NUMA
 #define NUMA_IMBALANCE_MIN 2
 
-static inline long
-adjust_numa_imbalance(int imbalance, int dst_running, int imb_numa_nr)
+long adjust_numa_imbalance(int imbalance, int dst_running, int imb_numa_nr)
 {
 	/*
 	 * Allow a NUMA imbalance if busy CPUs is less than the maximum
@@ -1670,8 +1622,7 @@ static unsigned long score_nearby_nodes(struct task_struct *p, int nid,
  * larger multiplier, in order to group tasks together that are almost
  * evenly spread out between numa nodes.
  */
-static inline unsigned long task_weight(struct task_struct *p, int nid,
-					int dist)
+unsigned long task_weight(struct task_struct *p, int nid, int dist)
 {
 	unsigned long faults, total_faults;
 
@@ -1689,8 +1640,7 @@ static inline unsigned long task_weight(struct task_struct *p, int nid,
 	return 1000 * faults / total_faults;
 }
 
-static inline unsigned long group_weight(struct task_struct *p, int nid,
-					 int dist)
+unsigned long group_weight(struct task_struct *p, int nid, int dist)
 {
 	struct numa_group *ng = deref_task_numa_group(p);
 	unsigned long faults, total_faults;
@@ -1982,7 +1932,6 @@ struct task_numa_env {
 };
 
 static unsigned long cpu_load(struct rq *rq);
-static unsigned long cpu_runnable(struct rq *rq);
 
 static inline enum
 numa_type numa_classify(unsigned int imbalance_pct,
@@ -3604,77 +3553,113 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
 		cfs_rq->idle_nr_running--;
 }
 
-/*
- * Signed add and clamp on underflow.
- *
- * Explicitly do a load-store to ensure the intermediate value never hits
- * memory. This allows lockless observations without ever seeing the negative
- * values.
- */
-#define add_positive(_ptr, _val) do {                           \
-	typeof(_ptr) ptr = (_ptr);                              \
-	typeof(_val) val = (_val);                              \
-	typeof(*ptr) res, var = READ_ONCE(*ptr);                \
-								\
-	res = var + val;                                        \
-								\
-	if (val < 0 && res > var)                               \
-		res = 0;                                        \
-								\
-	WRITE_ONCE(*ptr, res);                                  \
-} while (0)
+static void
+place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
+{
+	u64 vslice, vruntime = avg_vruntime(cfs_rq);
+	s64 lag = 0;
 
-/*
- * Unsigned subtract and clamp on underflow.
- *
- * Explicitly do a load-store to ensure the intermediate value never hits
- * memory. This allows lockless observations without ever seeing the negative
- * values.
- */
-#define sub_positive(_ptr, _val) do {				\
-	typeof(_ptr) ptr = (_ptr);				\
-	typeof(*ptr) val = (_val);				\
-	typeof(*ptr) res, var = READ_ONCE(*ptr);		\
-	res = var - val;					\
-	if (res > var)						\
-		res = 0;					\
-	WRITE_ONCE(*ptr, res);					\
-} while (0)
+	se->slice = sysctl_sched_base_slice;
+	vslice = calc_delta_fair(se->slice, se);
 
-/*
- * Remove and clamp on negative, from a local variable.
- *
- * A variant of sub_positive(), which does not use explicit load-store
- * and is thus optimized for local variable updates.
- */
-#define lsub_positive(_ptr, _val) do {				\
-	typeof(_ptr) ptr = (_ptr);				\
-	*ptr -= min_t(typeof(*ptr), *ptr, _val);		\
-} while (0)
+	/*
+	 * Due to how V is constructed as the weighted average of entities,
+	 * adding tasks with positive lag, or removing tasks with negative lag
+	 * will move 'time' backwards, this can screw around with the lag of
+	 * other tasks.
+	 *
+	 * EEVDF: placement strategy #1 / #2
+	 */
+	if (sched_feat(PLACE_LAG) && cfs_rq->nr_running) {
+		struct sched_entity *curr = cfs_rq->curr;
+		unsigned long load;
 
-#ifdef CONFIG_SMP
-static inline void
-enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
-	cfs_rq->avg.load_avg += se->avg.load_avg;
-	cfs_rq->avg.load_sum += se_weight(se) * se->avg.load_sum;
-}
+		lag = se->vlag;
 
-static inline void
-dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
-	sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg);
-	sub_positive(&cfs_rq->avg.load_sum, se_weight(se) * se->avg.load_sum);
-	/* See update_cfs_rq_load_avg() */
-	cfs_rq->avg.load_sum = max_t(u32, cfs_rq->avg.load_sum,
-					  cfs_rq->avg.load_avg * PELT_MIN_DIVIDER);
+		/*
+		 * If we want to place a task and preserve lag, we have to
+		 * consider the effect of the new entity on the weighted
+		 * average and compensate for this, otherwise lag can quickly
+		 * evaporate.
+		 *
+		 * Lag is defined as:
+		 *
+		 *   lag_i = S - s_i = w_i * (V - v_i)
+		 *
+		 * To avoid the 'w_i' term all over the place, we only track
+		 * the virtual lag:
+		 *
+		 *   vl_i = V - v_i <=> v_i = V - vl_i
+		 *
+		 * And we take V to be the weighted average of all v:
+		 *
+		 *   V = (\Sum w_j*v_j) / W
+		 *
+		 * Where W is: \Sum w_j
+		 *
+		 * Then, the weighted average after adding an entity with lag
+		 * vl_i is given by:
+		 *
+		 *   V' = (\Sum w_j*v_j + w_i*v_i) / (W + w_i)
+		 *      = (W*V + w_i*(V - vl_i)) / (W + w_i)
+		 *      = (W*V + w_i*V - w_i*vl_i) / (W + w_i)
+		 *      = (V*(W + w_i) - w_i*l) / (W + w_i)
+		 *      = V - w_i*vl_i / (W + w_i)
+		 *
+		 * And the actual lag after adding an entity with vl_i is:
+		 *
+		 *   vl'_i = V' - v_i
+		 *         = V - w_i*vl_i / (W + w_i) - (V - vl_i)
+		 *         = vl_i - w_i*vl_i / (W + w_i)
+		 *
+		 * Which is strictly less than vl_i. So in order to preserve lag
+		 * we should inflate the lag before placement such that the
+		 * effective lag after placement comes out right.
+		 *
+		 * As such, invert the above relation for vl'_i to get the vl_i
+		 * we need to use such that the lag after placement is the lag
+		 * we computed before dequeue.
+		 *
+		 *   vl'_i = vl_i - w_i*vl_i / (W + w_i)
+		 *         = ((W + w_i)*vl_i - w_i*vl_i) / (W + w_i)
+		 *
+		 *   (W + w_i)*vl'_i = (W + w_i)*vl_i - w_i*vl_i
+		 *                   = W*vl_i
+		 *
+		 *   vl_i = (W + w_i)*vl'_i / W
+		 */
+		load = cfs_rq->avg_load;
+		if (curr && curr->on_rq)
+			load += scale_load_down(curr->load.weight);
+
+		lag *= load + scale_load_down(se->load.weight);
+		if (WARN_ON_ONCE(!load))
+			load = 1;
+		lag = div_s64(lag, load);
+	}
+
+	se->vruntime = vruntime - lag;
+
+	/*
+	 * When joining the competition; the existing tasks will be,
+	 * on average, halfway through their slice, as such start tasks
+	 * off with half a slice to ease into the competition.
+	 */
+	if (sched_feat(PLACE_DEADLINE_INITIAL) && (flags & ENQUEUE_INITIAL))
+		vslice /= 2;
+
+	/*
+	 * EEVDF: vd_i = ve_i + r_i/w_i
+	 */
+	se->deadline = se->vruntime + vslice;
 }
-#else
-static inline void
-enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
-static inline void
-dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
-#endif
+
+static void check_enqueue_throttle(struct cfs_rq *cfs_rq);
+static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq);
+
+static inline bool cfs_bandwidth_used(void);
+
+static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
 
 static void reweight_eevdf(struct cfs_rq *cfs_rq, struct sched_entity *se,
 			   unsigned long weight)
@@ -3783,6 +3768,7 @@ static void reweight_eevdf(struct cfs_rq *cfs_rq, struct sched_entity *se,
 	se->deadline = avruntime + vslice;
 }
 
+
 static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
 			    unsigned long weight)
 {
@@ -3846,8 +3832,6 @@ void reweight_task(struct task_struct *p, int prio)
 	load->inv_weight = sched_prio_to_wmult[prio];
 }
 
-static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
-
 #ifdef CONFIG_FAIR_GROUP_SCHED
 #ifdef CONFIG_SMP
 /*
@@ -3988,8534 +3972,3292 @@ static inline void update_cfs_group(struct sched_entity *se)
 }
 #endif /* CONFIG_FAIR_GROUP_SCHED */
 
-static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq, int flags)
-{
-	struct rq *rq = rq_of(cfs_rq);
-
-	if (&rq->cfs == cfs_rq) {
-		/*
-		 * There are a few boundary cases this might miss but it should
-		 * get called often enough that that should (hopefully) not be
-		 * a real problem.
-		 *
-		 * It will not get called when we go idle, because the idle
-		 * thread is a different class (!fair), nor will the utilization
-		 * number include things like RT tasks.
-		 *
-		 * As is, the util number is not freq-invariant (we'd have to
-		 * implement arch_scale_freq_capacity() for that).
-		 *
-		 * See cpu_util_cfs().
-		 */
-		cpufreq_update_util(rq, flags);
-	}
-}
 
-#ifdef CONFIG_SMP
-static inline bool load_avg_is_decayed(struct sched_avg *sa)
+static void
+enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
 {
-	if (sa->load_sum)
-		return false;
+	bool curr = cfs_rq->curr == se;
 
-	if (sa->util_sum)
-		return false;
+	/*
+	 * If we're the current task, we must renormalise before calling
+	 * update_curr().
+	 */
+	if (curr)
+		place_entity(cfs_rq, se, flags);
 
-	if (sa->runnable_sum)
-		return false;
+	update_curr(cfs_rq);
 
 	/*
-	 * _avg must be null when _sum are null because _avg = _sum / divider
-	 * Make sure that rounding and/or propagation of PELT values never
-	 * break this.
+	 * When enqueuing a sched_entity, we must:
+	 *   - Update loads to have both entity and cfs_rq synced with now.
+	 *   - For group_entity, update its runnable_weight to reflect the new
+	 *     h_nr_running of its group cfs_rq.
+	 *   - For group_entity, update its weight to reflect the new share of
+	 *     its group cfs_rq
+	 *   - Add its new weight to cfs_rq->load.weight
+	 */
+	update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
+	se_update_runnable(se);
+	/*
+	 * XXX update_load_avg() above will have attached us to the pelt sum;
+	 * but update_cfs_group() here will re-adjust the weight and have to
+	 * undo/redo all that. Seems wasteful.
 	 */
-	SCHED_WARN_ON(sa->load_avg ||
-		      sa->util_avg ||
-		      sa->runnable_avg);
+	update_cfs_group(se);
 
-	return true;
-}
+	/*
+	 * XXX now that the entity has been re-weighted, and it's lag adjusted,
+	 * we can place the entity.
+	 */
+	if (!curr)
+		place_entity(cfs_rq, se, flags);
 
-static inline u64 cfs_rq_last_update_time(struct cfs_rq *cfs_rq)
-{
-	return u64_u32_load_copy(cfs_rq->avg.last_update_time,
-				 cfs_rq->last_update_time_copy);
-}
-#ifdef CONFIG_FAIR_GROUP_SCHED
-/*
- * Because list_add_leaf_cfs_rq always places a child cfs_rq on the list
- * immediately before a parent cfs_rq, and cfs_rqs are removed from the list
- * bottom-up, we only have to test whether the cfs_rq before us on the list
- * is our child.
- * If cfs_rq is not on the list, test whether a child needs its to be added to
- * connect a branch to the tree  * (see list_add_leaf_cfs_rq() for details).
- */
-static inline bool child_cfs_rq_on_list(struct cfs_rq *cfs_rq)
-{
-	struct cfs_rq *prev_cfs_rq;
-	struct list_head *prev;
+	account_entity_enqueue(cfs_rq, se);
 
-	if (cfs_rq->on_list) {
-		prev = cfs_rq->leaf_cfs_rq_list.prev;
-	} else {
-		struct rq *rq = rq_of(cfs_rq);
+	/* Entity has migrated, no longer consider this task hot */
+	if (flags & ENQUEUE_MIGRATED)
+		se->exec_start = 0;
 
-		prev = rq->tmp_alone_branch;
-	}
+	check_schedstat_required();
+	update_stats_enqueue_fair(cfs_rq, se, flags);
+	if (!curr)
+		__enqueue_entity(cfs_rq, se);
+	se->on_rq = 1;
 
-	prev_cfs_rq = container_of(prev, struct cfs_rq, leaf_cfs_rq_list);
+	if (cfs_rq->nr_running == 1) {
+		check_enqueue_throttle(cfs_rq);
+		if (!throttled_hierarchy(cfs_rq)) {
+			list_add_leaf_cfs_rq(cfs_rq);
+		} else {
+#ifdef CONFIG_CFS_BANDWIDTH
+			struct rq *rq = rq_of(cfs_rq);
 
-	return (prev_cfs_rq->tg->parent == cfs_rq->tg);
+			if (cfs_rq_throttled(cfs_rq) && !cfs_rq->throttled_clock)
+				cfs_rq->throttled_clock = rq_clock(rq);
+			if (!cfs_rq->throttled_clock_self)
+				cfs_rq->throttled_clock_self = rq_clock(rq);
+#endif
+		}
+	}
 }
 
-static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
+static void __clear_buddies_next(struct sched_entity *se)
 {
-	if (cfs_rq->load.weight)
-		return false;
-
-	if (!load_avg_is_decayed(&cfs_rq->avg))
-		return false;
-
-	if (child_cfs_rq_on_list(cfs_rq))
-		return false;
+	for_each_sched_entity(se) {
+		struct cfs_rq *cfs_rq = cfs_rq_of(se);
+		if (cfs_rq->next != se)
+			break;
 
-	return true;
+		cfs_rq->next = NULL;
+	}
 }
 
-/**
- * update_tg_load_avg - update the tg's load avg
- * @cfs_rq: the cfs_rq whose avg changed
- *
- * This function 'ensures': tg->load_avg := \Sum tg->cfs_rq[]->avg.load.
- * However, because tg->load_avg is a global value there are performance
- * considerations.
- *
- * In order to avoid having to look at the other cfs_rq's, we use a
- * differential update where we store the last value we propagated. This in
- * turn allows skipping updates if the differential is 'small'.
- *
- * Updating tg's load_avg is necessary before update_cfs_share().
- */
-static inline void update_tg_load_avg(struct cfs_rq *cfs_rq)
+static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-	long delta;
-	u64 now;
+	if (cfs_rq->next == se)
+		__clear_buddies_next(se);
+}
 
-	/*
-	 * No need to update load_avg for root_task_group as it is not used.
-	 */
-	if (cfs_rq->tg == &root_task_group)
-		return;
+static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
 
-	/* rq has been offline and doesn't contribute to the share anymore: */
-	if (!cpu_active(cpu_of(rq_of(cfs_rq))))
-		return;
+static void
+dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
+{
+	int action = UPDATE_TG;
+
+	if (entity_is_task(se) && task_on_rq_migrating(task_of(se)))
+		action |= DO_DETACH;
 
 	/*
-	 * For migration heavy workloads, access to tg->load_avg can be
-	 * unbound. Limit the update rate to at most once per ms.
+	 * Update run-time statistics of the 'current'.
 	 */
-	now = sched_clock_cpu(cpu_of(rq_of(cfs_rq)));
-	if (now - cfs_rq->last_update_tg_load_avg < NSEC_PER_MSEC)
-		return;
-
-	delta = cfs_rq->avg.load_avg - cfs_rq->tg_load_avg_contrib;
-	if (abs(delta) > cfs_rq->tg_load_avg_contrib / 64) {
-		atomic_long_add(delta, &cfs_rq->tg->load_avg);
-		cfs_rq->tg_load_avg_contrib = cfs_rq->avg.load_avg;
-		cfs_rq->last_update_tg_load_avg = now;
-	}
-}
-
-static inline void clear_tg_load_avg(struct cfs_rq *cfs_rq)
-{
-	long delta;
-	u64 now;
+	update_curr(cfs_rq);
 
 	/*
-	 * No need to update load_avg for root_task_group, as it is not used.
+	 * When dequeuing a sched_entity, we must:
+	 *   - Update loads to have both entity and cfs_rq synced with now.
+	 *   - For group_entity, update its runnable_weight to reflect the new
+	 *     h_nr_running of its group cfs_rq.
+	 *   - Subtract its previous weight from cfs_rq->load.weight.
+	 *   - For group entity, update its weight to reflect the new share
+	 *     of its group cfs_rq.
 	 */
-	if (cfs_rq->tg == &root_task_group)
-		return;
+	update_load_avg(cfs_rq, se, action);
+	se_update_runnable(se);
 
-	now = sched_clock_cpu(cpu_of(rq_of(cfs_rq)));
-	delta = 0 - cfs_rq->tg_load_avg_contrib;
-	atomic_long_add(delta, &cfs_rq->tg->load_avg);
-	cfs_rq->tg_load_avg_contrib = 0;
-	cfs_rq->last_update_tg_load_avg = now;
-}
+	update_stats_dequeue_fair(cfs_rq, se, flags);
 
-/* CPU offline callback: */
-static void __maybe_unused clear_tg_offline_cfs_rqs(struct rq *rq)
-{
-	struct task_group *tg;
+	clear_buddies(cfs_rq, se);
 
-	lockdep_assert_rq_held(rq);
+	update_entity_lag(cfs_rq, se);
+	if (se != cfs_rq->curr)
+		__dequeue_entity(cfs_rq, se);
+	se->on_rq = 0;
+	account_entity_dequeue(cfs_rq, se);
 
-	/*
-	 * The rq clock has already been updated in
-	 * set_rq_offline(), so we should skip updating
-	 * the rq clock again in unthrottle_cfs_rq().
-	 */
-	rq_clock_start_loop_update(rq);
+	/* return excess runtime on last dequeue */
+	return_cfs_rq_runtime(cfs_rq);
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(tg, &task_groups, list) {
-		struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
+	update_cfs_group(se);
 
-		clear_tg_load_avg(cfs_rq);
-	}
-	rcu_read_unlock();
+	/*
+	 * Now advance min_vruntime if @se was the entity holding it back,
+	 * except when: DEQUEUE_SAVE && !DEQUEUE_MOVE, in this case we'll be
+	 * put back on, and if we advance min_vruntime, we'll be placed back
+	 * further than we started -- i.e. we'll be penalized.
+	 */
+	if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) != DEQUEUE_SAVE)
+		update_min_vruntime(cfs_rq);
 
-	rq_clock_stop_loop_update(rq);
+	if (cfs_rq->nr_running == 0)
+		update_idle_cfs_rq_clock_pelt(cfs_rq);
 }
 
-/*
- * Called within set_task_rq() right before setting a task's CPU. The
- * caller only guarantees p->pi_lock is held; no other assumptions,
- * including the state of rq->lock, should be made.
- */
-void set_task_rq_fair(struct sched_entity *se,
-		      struct cfs_rq *prev, struct cfs_rq *next)
+static void
+set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
-	u64 p_last_update_time;
-	u64 n_last_update_time;
+	clear_buddies(cfs_rq, se);
 
-	if (!sched_feat(ATTACH_AGE_LOAD))
-		return;
+	/* 'current' is not kept within the tree. */
+	if (se->on_rq) {
+		/*
+		 * Any task has to be enqueued before it get to execute on
+		 * a CPU. So account for the time it spent waiting on the
+		 * runqueue.
+		 */
+		update_stats_wait_end_fair(cfs_rq, se);
+		__dequeue_entity(cfs_rq, se);
+		update_load_avg(cfs_rq, se, UPDATE_TG);
+		/*
+		 * HACK, stash a copy of deadline at the point of pick in vlag,
+		 * which isn't used until dequeue.
+		 */
+		se->vlag = se->deadline;
+	}
+
+	update_stats_curr_start(cfs_rq, se);
+	cfs_rq->curr = se;
 
 	/*
-	 * We are supposed to update the task to "current" time, then its up to
-	 * date and ready to go to new CPU/cfs_rq. But we have difficulty in
-	 * getting what current time is, so simply throw away the out-of-date
-	 * time. This will result in the wakee task is less decayed, but giving
-	 * the wakee more load sounds not bad.
+	 * Track our maximum slice length, if the CPU's load is at
+	 * least twice that of our own weight (i.e. don't track it
+	 * when there are only lesser-weight tasks around):
 	 */
-	if (!(se->avg.last_update_time && prev))
-		return;
+	if (schedstat_enabled() &&
+	    rq_of(cfs_rq)->cfs.load.weight >= 2*se->load.weight) {
+		struct sched_statistics *stats;
 
-	p_last_update_time = cfs_rq_last_update_time(prev);
-	n_last_update_time = cfs_rq_last_update_time(next);
+		stats = __schedstats_from_se(se);
+		__schedstat_set(stats->slice_max,
+				max((u64)stats->slice_max,
+				    se->sum_exec_runtime - se->prev_sum_exec_runtime));
+	}
 
-	__update_load_avg_blocked_se(p_last_update_time, se);
-	se->avg.last_update_time = n_last_update_time;
+	se->prev_sum_exec_runtime = se->sum_exec_runtime;
 }
 
 /*
- * When on migration a sched_entity joins/leaves the PELT hierarchy, we need to
- * propagate its contribution. The key to this propagation is the invariant
- * that for each group:
- *
- *   ge->avg == grq->avg						(1)
- *
- * _IFF_ we look at the pure running and runnable sums. Because they
- * represent the very same entity, just at different points in the hierarchy.
- *
- * Per the above update_tg_cfs_util() and update_tg_cfs_runnable() are trivial
- * and simply copies the running/runnable sum over (but still wrong, because
- * the group entity and group rq do not have their PELT windows aligned).
- *
- * However, update_tg_cfs_load() is more complex. So we have:
- *
- *   ge->avg.load_avg = ge->load.weight * ge->avg.runnable_avg		(2)
- *
- * And since, like util, the runnable part should be directly transferable,
- * the following would _appear_ to be the straight forward approach:
- *
- *   grq->avg.load_avg = grq->load.weight * grq->avg.runnable_avg	(3)
- *
- * And per (1) we have:
- *
- *   ge->avg.runnable_avg == grq->avg.runnable_avg
- *
- * Which gives:
- *
- *                      ge->load.weight * grq->avg.load_avg
- *   ge->avg.load_avg = -----------------------------------		(4)
- *                               grq->load.weight
- *
- * Except that is wrong!
- *
- * Because while for entities historical weight is not important and we
- * really only care about our future and therefore can consider a pure
- * runnable sum, runqueues can NOT do this.
- *
- * We specifically want runqueues to have a load_avg that includes
- * historical weights. Those represent the blocked load, the load we expect
- * to (shortly) return to us. This only works by keeping the weights as
- * integral part of the sum. We therefore cannot decompose as per (3).
- *
- * Another reason this doesn't work is that runnable isn't a 0-sum entity.
- * Imagine a rq with 2 tasks that each are runnable 2/3 of the time. Then the
- * rq itself is runnable anywhere between 2/3 and 1 depending on how the
- * runnable section of these tasks overlap (or not). If they were to perfectly
- * align the rq as a whole would be runnable 2/3 of the time. If however we
- * always have at least 1 runnable task, the rq as a whole is always runnable.
- *
- * So we'll have to approximate.. :/
- *
- * Given the constraint:
- *
- *   ge->avg.running_sum <= ge->avg.runnable_sum <= LOAD_AVG_MAX
- *
- * We can construct a rule that adds runnable to a rq by assuming minimal
- * overlap.
- *
- * On removal, we'll assume each task is equally runnable; which yields:
- *
- *   grq->avg.runnable_sum = grq->avg.load_sum / grq->load.weight
- *
- * XXX: only do this for the part of runnable > running ?
- *
+ * Pick the next process, keeping these things in mind, in this order:
+ * 1) keep things fair between processes/task groups
+ * 2) pick the "next" process, since someone really wants that to run
+ * 3) pick the "last" process, for cache locality
+ * 4) do not run the "skip" process, if something else is available
  */
-static inline void
-update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
+static struct sched_entity *
+pick_next_entity(struct cfs_rq *cfs_rq)
 {
-	long delta_sum, delta_avg = gcfs_rq->avg.util_avg - se->avg.util_avg;
-	u32 new_sum, divider;
-
-	/* Nothing to update */
-	if (!delta_avg)
-		return;
-
 	/*
-	 * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
-	 * See ___update_load_avg() for details.
+	 * Enabling NEXT_BUDDY will affect latency but not fairness.
 	 */
-	divider = get_pelt_divider(&cfs_rq->avg);
-
-
-	/* Set new sched_entity's utilization */
-	se->avg.util_avg = gcfs_rq->avg.util_avg;
-	new_sum = se->avg.util_avg * divider;
-	delta_sum = (long)new_sum - (long)se->avg.util_sum;
-	se->avg.util_sum = new_sum;
-
-	/* Update parent cfs_rq utilization */
-	add_positive(&cfs_rq->avg.util_avg, delta_avg);
-	add_positive(&cfs_rq->avg.util_sum, delta_sum);
+	if (sched_feat(NEXT_BUDDY) &&
+	    cfs_rq->next && entity_eligible(cfs_rq, cfs_rq->next))
+		return cfs_rq->next;
 
-	/* See update_cfs_rq_load_avg() */
-	cfs_rq->avg.util_sum = max_t(u32, cfs_rq->avg.util_sum,
-					  cfs_rq->avg.util_avg * PELT_MIN_DIVIDER);
+	return pick_eevdf(cfs_rq);
 }
 
-static inline void
-update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
-{
-	long delta_sum, delta_avg = gcfs_rq->avg.runnable_avg - se->avg.runnable_avg;
-	u32 new_sum, divider;
-
-	/* Nothing to update */
-	if (!delta_avg)
-		return;
+static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
 
+static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
+{
 	/*
-	 * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
-	 * See ___update_load_avg() for details.
+	 * If still on the runqueue then deactivate_task()
+	 * was not called and update_curr() has to be done:
 	 */
-	divider = get_pelt_divider(&cfs_rq->avg);
+	if (prev->on_rq)
+		update_curr(cfs_rq);
 
-	/* Set new sched_entity's runnable */
-	se->avg.runnable_avg = gcfs_rq->avg.runnable_avg;
-	new_sum = se->avg.runnable_avg * divider;
-	delta_sum = (long)new_sum - (long)se->avg.runnable_sum;
-	se->avg.runnable_sum = new_sum;
+	/* throttle cfs_rqs exceeding runtime */
+	check_cfs_rq_runtime(cfs_rq);
 
-	/* Update parent cfs_rq runnable */
-	add_positive(&cfs_rq->avg.runnable_avg, delta_avg);
-	add_positive(&cfs_rq->avg.runnable_sum, delta_sum);
-	/* See update_cfs_rq_load_avg() */
-	cfs_rq->avg.runnable_sum = max_t(u32, cfs_rq->avg.runnable_sum,
-					      cfs_rq->avg.runnable_avg * PELT_MIN_DIVIDER);
+	if (prev->on_rq) {
+		update_stats_wait_start_fair(cfs_rq, prev);
+		/* Put 'current' back into the tree. */
+		__enqueue_entity(cfs_rq, prev);
+		/* in !on_rq case, update occurred at dequeue */
+		update_load_avg(cfs_rq, prev, 0);
+	}
+	cfs_rq->curr = NULL;
 }
 
-static inline void
-update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
+static void
+entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
 {
-	long delta_avg, running_sum, runnable_sum = gcfs_rq->prop_runnable_sum;
-	unsigned long load_avg;
-	u64 load_sum = 0;
-	s64 delta_sum;
-	u32 divider;
-
-	if (!runnable_sum)
-		return;
-
-	gcfs_rq->prop_runnable_sum = 0;
-
 	/*
-	 * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
-	 * See ___update_load_avg() for details.
+	 * Update run-time statistics of the 'current'.
 	 */
-	divider = get_pelt_divider(&cfs_rq->avg);
+	update_curr(cfs_rq);
 
-	if (runnable_sum >= 0) {
-		/*
-		 * Add runnable; clip at LOAD_AVG_MAX. Reflects that until
-		 * the CPU is saturated running == runnable.
-		 */
-		runnable_sum += se->avg.load_sum;
-		runnable_sum = min_t(long, runnable_sum, divider);
-	} else {
-		/*
-		 * Estimate the new unweighted runnable_sum of the gcfs_rq by
-		 * assuming all tasks are equally runnable.
-		 */
-		if (scale_load_down(gcfs_rq->load.weight)) {
-			load_sum = div_u64(gcfs_rq->avg.load_sum,
-				scale_load_down(gcfs_rq->load.weight));
-		}
+	/*
+	 * Ensure that runnable average is periodically updated.
+	 */
+	update_load_avg(cfs_rq, curr, UPDATE_TG);
+	update_cfs_group(curr);
 
-		/* But make sure to not inflate se's runnable */
-		runnable_sum = min(se->avg.load_sum, load_sum);
+#ifdef CONFIG_SCHED_HRTICK
+	/*
+	 * queued ticks are scheduled to match the slice, so don't bother
+	 * validating it and just reschedule.
+	 */
+	if (queued) {
+		resched_curr(rq_of(cfs_rq));
+		return;
 	}
-
 	/*
-	 * runnable_sum can't be lower than running_sum
-	 * Rescale running sum to be in the same range as runnable sum
-	 * running_sum is in [0 : LOAD_AVG_MAX <<  SCHED_CAPACITY_SHIFT]
-	 * runnable_sum is in [0 : LOAD_AVG_MAX]
+	 * don't let the period tick interfere with the hrtick preemption
 	 */
-	running_sum = se->avg.util_sum >> SCHED_CAPACITY_SHIFT;
-	runnable_sum = max(runnable_sum, running_sum);
+	if (!sched_feat(DOUBLE_TICK) &&
+			hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
+		return;
+#endif
+}
 
-	load_sum = se_weight(se) * runnable_sum;
-	load_avg = div_u64(load_sum, divider);
 
-	delta_avg = load_avg - se->avg.load_avg;
-	if (!delta_avg)
-		return;
+/**************************************************
+ * CFS bandwidth control machinery
+ */
 
-	delta_sum = load_sum - (s64)se_weight(se) * se->avg.load_sum;
+#ifdef CONFIG_CFS_BANDWIDTH
 
-	se->avg.load_sum = runnable_sum;
-	se->avg.load_avg = load_avg;
-	add_positive(&cfs_rq->avg.load_avg, delta_avg);
-	add_positive(&cfs_rq->avg.load_sum, delta_sum);
-	/* See update_cfs_rq_load_avg() */
-	cfs_rq->avg.load_sum = max_t(u32, cfs_rq->avg.load_sum,
-					  cfs_rq->avg.load_avg * PELT_MIN_DIVIDER);
-}
+#ifdef CONFIG_JUMP_LABEL
+static struct static_key __cfs_bandwidth_used;
 
-static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum)
+static inline bool cfs_bandwidth_used(void)
 {
-	cfs_rq->propagate = 1;
-	cfs_rq->prop_runnable_sum += runnable_sum;
+	return static_key_false(&__cfs_bandwidth_used);
 }
 
-/* Update task and its cfs_rq load average */
-static inline int propagate_entity_load_avg(struct sched_entity *se)
+void cfs_bandwidth_usage_inc(void)
 {
-	struct cfs_rq *cfs_rq, *gcfs_rq;
-
-	if (entity_is_task(se))
-		return 0;
-
-	gcfs_rq = group_cfs_rq(se);
-	if (!gcfs_rq->propagate)
-		return 0;
-
-	gcfs_rq->propagate = 0;
-
-	cfs_rq = cfs_rq_of(se);
+	static_key_slow_inc_cpuslocked(&__cfs_bandwidth_used);
+}
 
-	add_tg_cfs_propagate(cfs_rq, gcfs_rq->prop_runnable_sum);
+void cfs_bandwidth_usage_dec(void)
+{
+	static_key_slow_dec_cpuslocked(&__cfs_bandwidth_used);
+}
+#else /* CONFIG_JUMP_LABEL */
+static bool cfs_bandwidth_used(void)
+{
+	return true;
+}
 
-	update_tg_cfs_util(cfs_rq, se, gcfs_rq);
-	update_tg_cfs_runnable(cfs_rq, se, gcfs_rq);
-	update_tg_cfs_load(cfs_rq, se, gcfs_rq);
+void cfs_bandwidth_usage_inc(void) {}
+void cfs_bandwidth_usage_dec(void) {}
+#endif /* CONFIG_JUMP_LABEL */
 
-	trace_pelt_cfs_tp(cfs_rq);
-	trace_pelt_se_tp(se);
+/*
+ * default period for cfs group bandwidth.
+ * default: 0.1s, units: nanoseconds
+ */
+static inline u64 default_cfs_period(void)
+{
+	return 100000000ULL;
+}
 
-	return 1;
+static inline u64 sched_cfs_bandwidth_slice(void)
+{
+	return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
 }
 
 /*
- * Check if we need to update the load and the utilization of a blocked
- * group_entity:
+ * Replenish runtime according to assigned quota. We use sched_clock_cpu
+ * directly instead of rq->clock to avoid adding additional synchronization
+ * around rq->lock.
+ *
+ * requires cfs_b->lock
  */
-static inline bool skip_blocked_update(struct sched_entity *se)
+void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
 {
-	struct cfs_rq *gcfs_rq = group_cfs_rq(se);
+	s64 runtime;
 
-	/*
-	 * If sched_entity still have not zero load or utilization, we have to
-	 * decay it:
-	 */
-	if (se->avg.load_avg || se->avg.util_avg)
-		return false;
+	if (unlikely(cfs_b->quota == RUNTIME_INF))
+		return;
 
-	/*
-	 * If there is a pending propagation, we have to update the load and
-	 * the utilization of the sched_entity:
-	 */
-	if (gcfs_rq->propagate)
-		return false;
+	cfs_b->runtime += cfs_b->quota;
+	runtime = cfs_b->runtime_snap - cfs_b->runtime;
+	if (runtime > 0) {
+		cfs_b->burst_time += runtime;
+		cfs_b->nr_burst++;
+	}
 
-	/*
-	 * Otherwise, the load and the utilization of the sched_entity is
-	 * already zero and there is no pending propagation, so it will be a
-	 * waste of time to try to decay it:
-	 */
-	return true;
+	cfs_b->runtime = min(cfs_b->runtime, cfs_b->quota + cfs_b->burst);
+	cfs_b->runtime_snap = cfs_b->runtime;
 }
 
-#else /* CONFIG_FAIR_GROUP_SCHED */
-
-static inline void update_tg_load_avg(struct cfs_rq *cfs_rq) {}
-
-static inline void clear_tg_offline_cfs_rqs(struct rq *rq) {}
-
-static inline int propagate_entity_load_avg(struct sched_entity *se)
+static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
 {
-	return 0;
+	return &tg->cfs_bandwidth;
 }
 
-static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum) {}
-
-#endif /* CONFIG_FAIR_GROUP_SCHED */
-
-#ifdef CONFIG_NO_HZ_COMMON
-static inline void migrate_se_pelt_lag(struct sched_entity *se)
+/* returns 0 on failure to allocate runtime */
+static int __assign_cfs_rq_runtime(struct cfs_bandwidth *cfs_b,
+				   struct cfs_rq *cfs_rq, u64 target_runtime)
 {
-	u64 throttled = 0, now, lut;
-	struct cfs_rq *cfs_rq;
-	struct rq *rq;
-	bool is_idle;
-
-	if (load_avg_is_decayed(&se->avg))
-		return;
-
-	cfs_rq = cfs_rq_of(se);
-	rq = rq_of(cfs_rq);
+	u64 min_amount, amount = 0;
 
-	rcu_read_lock();
-	is_idle = is_idle_task(rcu_dereference(rq->curr));
-	rcu_read_unlock();
+	lockdep_assert_held(&cfs_b->lock);
 
-	/*
-	 * The lag estimation comes with a cost we don't want to pay all the
-	 * time. Hence, limiting to the case where the source CPU is idle and
-	 * we know we are at the greatest risk to have an outdated clock.
-	 */
-	if (!is_idle)
-		return;
+	/* note: this is a positive sum as runtime_remaining <= 0 */
+	min_amount = target_runtime - cfs_rq->runtime_remaining;
 
-	/*
-	 * Estimated "now" is: last_update_time + cfs_idle_lag + rq_idle_lag, where:
-	 *
-	 *   last_update_time (the cfs_rq's last_update_time)
-	 *	= cfs_rq_clock_pelt()@cfs_rq_idle
-	 *      = rq_clock_pelt()@cfs_rq_idle
-	 *        - cfs->throttled_clock_pelt_time@cfs_rq_idle
-	 *
-	 *   cfs_idle_lag (delta between rq's update and cfs_rq's update)
-	 *      = rq_clock_pelt()@rq_idle - rq_clock_pelt()@cfs_rq_idle
-	 *
-	 *   rq_idle_lag (delta between now and rq's update)
-	 *      = sched_clock_cpu() - rq_clock()@rq_idle
-	 *
-	 * We can then write:
-	 *
-	 *    now = rq_clock_pelt()@rq_idle - cfs->throttled_clock_pelt_time +
-	 *          sched_clock_cpu() - rq_clock()@rq_idle
-	 * Where:
-	 *      rq_clock_pelt()@rq_idle is rq->clock_pelt_idle
-	 *      rq_clock()@rq_idle      is rq->clock_idle
-	 *      cfs->throttled_clock_pelt_time@cfs_rq_idle
-	 *                              is cfs_rq->throttled_pelt_idle
-	 */
+	if (cfs_b->quota == RUNTIME_INF)
+		amount = min_amount;
+	else {
+		start_cfs_bandwidth(cfs_b);
 
-#ifdef CONFIG_CFS_BANDWIDTH
-	throttled = u64_u32_load(cfs_rq->throttled_pelt_idle);
-	/* The clock has been stopped for throttling */
-	if (throttled == U64_MAX)
-		return;
-#endif
-	now = u64_u32_load(rq->clock_pelt_idle);
-	/*
-	 * Paired with _update_idle_rq_clock_pelt(). It ensures at the worst case
-	 * is observed the old clock_pelt_idle value and the new clock_idle,
-	 * which lead to an underestimation. The opposite would lead to an
-	 * overestimation.
-	 */
-	smp_rmb();
-	lut = cfs_rq_last_update_time(cfs_rq);
+		if (cfs_b->runtime > 0) {
+			amount = min(cfs_b->runtime, min_amount);
+			cfs_b->runtime -= amount;
+			cfs_b->idle = 0;
+		}
+	}
 
-	now -= throttled;
-	if (now < lut)
-		/*
-		 * cfs_rq->avg.last_update_time is more recent than our
-		 * estimation, let's use it.
-		 */
-		now = lut;
-	else
-		now += sched_clock_cpu(cpu_of(rq)) - u64_u32_load(rq->clock_idle);
+	cfs_rq->runtime_remaining += amount;
 
-	__update_load_avg_blocked_se(now, se);
+	return cfs_rq->runtime_remaining > 0;
 }
-#else
-static void migrate_se_pelt_lag(struct sched_entity *se) {}
-#endif
-
-/**
- * update_cfs_rq_load_avg - update the cfs_rq's load/util averages
- * @now: current time, as per cfs_rq_clock_pelt()
- * @cfs_rq: cfs_rq to update
- *
- * The cfs_rq avg is the direct sum of all its entities (blocked and runnable)
- * avg. The immediate corollary is that all (fair) tasks must be attached.
- *
- * cfs_rq->avg is used for task_h_load() and update_cfs_share() for example.
- *
- * Return: true if the load decayed or we removed load.
- *
- * Since both these conditions indicate a changed cfs_rq->avg.load we should
- * call update_tg_load_avg() when this function returns true.
- */
-static inline int
-update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
-{
-	unsigned long removed_load = 0, removed_util = 0, removed_runnable = 0;
-	struct sched_avg *sa = &cfs_rq->avg;
-	int decayed = 0;
-
-	if (cfs_rq->removed.nr) {
-		unsigned long r;
-		u32 divider = get_pelt_divider(&cfs_rq->avg);
-
-		raw_spin_lock(&cfs_rq->removed.lock);
-		swap(cfs_rq->removed.util_avg, removed_util);
-		swap(cfs_rq->removed.load_avg, removed_load);
-		swap(cfs_rq->removed.runnable_avg, removed_runnable);
-		cfs_rq->removed.nr = 0;
-		raw_spin_unlock(&cfs_rq->removed.lock);
-
-		r = removed_load;
-		sub_positive(&sa->load_avg, r);
-		sub_positive(&sa->load_sum, r * divider);
-		/* See sa->util_sum below */
-		sa->load_sum = max_t(u32, sa->load_sum, sa->load_avg * PELT_MIN_DIVIDER);
-
-		r = removed_util;
-		sub_positive(&sa->util_avg, r);
-		sub_positive(&sa->util_sum, r * divider);
-		/*
-		 * Because of rounding, se->util_sum might ends up being +1 more than
-		 * cfs->util_sum. Although this is not a problem by itself, detaching
-		 * a lot of tasks with the rounding problem between 2 updates of
-		 * util_avg (~1ms) can make cfs->util_sum becoming null whereas
-		 * cfs_util_avg is not.
-		 * Check that util_sum is still above its lower bound for the new
-		 * util_avg. Given that period_contrib might have moved since the last
-		 * sync, we are only sure that util_sum must be above or equal to
-		 *    util_avg * minimum possible divider
-		 */
-		sa->util_sum = max_t(u32, sa->util_sum, sa->util_avg * PELT_MIN_DIVIDER);
-
-		r = removed_runnable;
-		sub_positive(&sa->runnable_avg, r);
-		sub_positive(&sa->runnable_sum, r * divider);
-		/* See sa->util_sum above */
-		sa->runnable_sum = max_t(u32, sa->runnable_sum,
-					      sa->runnable_avg * PELT_MIN_DIVIDER);
 
-		/*
-		 * removed_runnable is the unweighted version of removed_load so we
-		 * can use it to estimate removed_load_sum.
-		 */
-		add_tg_cfs_propagate(cfs_rq,
-			-(long)(removed_runnable * divider) >> SCHED_CAPACITY_SHIFT);
+/* returns 0 on failure to allocate runtime */
+static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+{
+	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+	int ret;
 
-		decayed = 1;
-	}
+	raw_spin_lock(&cfs_b->lock);
+	ret = __assign_cfs_rq_runtime(cfs_b, cfs_rq, sched_cfs_bandwidth_slice());
+	raw_spin_unlock(&cfs_b->lock);
 
-	decayed |= __update_load_avg_cfs_rq(now, cfs_rq);
-	u64_u32_store_copy(sa->last_update_time,
-			   cfs_rq->last_update_time_copy,
-			   sa->last_update_time);
-	return decayed;
+	return ret;
 }
 
-/**
- * attach_entity_load_avg - attach this entity to its cfs_rq load avg
- * @cfs_rq: cfs_rq to attach to
- * @se: sched_entity to attach
- *
- * Must call update_cfs_rq_load_avg() before this, since we rely on
- * cfs_rq->avg.last_update_time being current.
- */
-static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
 {
-	/*
-	 * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
-	 * See ___update_load_avg() for details.
-	 */
-	u32 divider = get_pelt_divider(&cfs_rq->avg);
+	/* dock delta_exec before expiring quota (as it could span periods) */
+	cfs_rq->runtime_remaining -= delta_exec;
 
-	/*
-	 * When we attach the @se to the @cfs_rq, we must align the decay
-	 * window because without that, really weird and wonderful things can
-	 * happen.
-	 *
-	 * XXX illustrate
-	 */
-	se->avg.last_update_time = cfs_rq->avg.last_update_time;
-	se->avg.period_contrib = cfs_rq->avg.period_contrib;
+	if (likely(cfs_rq->runtime_remaining > 0))
+		return;
 
+	if (cfs_rq->throttled)
+		return;
 	/*
-	 * Hell(o) Nasty stuff.. we need to recompute _sum based on the new
-	 * period_contrib. This isn't strictly correct, but since we're
-	 * entirely outside of the PELT hierarchy, nobody cares if we truncate
-	 * _sum a little.
+	 * if we're unable to extend our runtime we resched so that the active
+	 * hierarchy can be throttled
 	 */
-	se->avg.util_sum = se->avg.util_avg * divider;
-
-	se->avg.runnable_sum = se->avg.runnable_avg * divider;
-
-	se->avg.load_sum = se->avg.load_avg * divider;
-	if (se_weight(se) < se->avg.load_sum)
-		se->avg.load_sum = div_u64(se->avg.load_sum, se_weight(se));
-	else
-		se->avg.load_sum = 1;
-
-	enqueue_load_avg(cfs_rq, se);
-	cfs_rq->avg.util_avg += se->avg.util_avg;
-	cfs_rq->avg.util_sum += se->avg.util_sum;
-	cfs_rq->avg.runnable_avg += se->avg.runnable_avg;
-	cfs_rq->avg.runnable_sum += se->avg.runnable_sum;
-
-	add_tg_cfs_propagate(cfs_rq, se->avg.load_sum);
-
-	cfs_rq_util_change(cfs_rq, 0);
-
-	trace_pelt_cfs_tp(cfs_rq);
+	if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
+		resched_curr(rq_of(cfs_rq));
 }
 
-/**
- * detach_entity_load_avg - detach this entity from its cfs_rq load avg
- * @cfs_rq: cfs_rq to detach from
- * @se: sched_entity to detach
- *
- * Must call update_cfs_rq_load_avg() before this, since we rely on
- * cfs_rq->avg.last_update_time being current.
- */
-static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+static __always_inline
+void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
 {
-	dequeue_load_avg(cfs_rq, se);
-	sub_positive(&cfs_rq->avg.util_avg, se->avg.util_avg);
-	sub_positive(&cfs_rq->avg.util_sum, se->avg.util_sum);
-	/* See update_cfs_rq_load_avg() */
-	cfs_rq->avg.util_sum = max_t(u32, cfs_rq->avg.util_sum,
-					  cfs_rq->avg.util_avg * PELT_MIN_DIVIDER);
-
-	sub_positive(&cfs_rq->avg.runnable_avg, se->avg.runnable_avg);
-	sub_positive(&cfs_rq->avg.runnable_sum, se->avg.runnable_sum);
-	/* See update_cfs_rq_load_avg() */
-	cfs_rq->avg.runnable_sum = max_t(u32, cfs_rq->avg.runnable_sum,
-					      cfs_rq->avg.runnable_avg * PELT_MIN_DIVIDER);
-
-	add_tg_cfs_propagate(cfs_rq, -se->avg.load_sum);
-
-	cfs_rq_util_change(cfs_rq, 0);
+	if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled)
+		return;
 
-	trace_pelt_cfs_tp(cfs_rq);
+	__account_cfs_rq_runtime(cfs_rq, delta_exec);
 }
 
-/*
- * Optional action to be done while updating the load average
- */
-#define UPDATE_TG	0x1
-#define SKIP_AGE_LOAD	0x2
-#define DO_ATTACH	0x4
-#define DO_DETACH	0x8
-
-/* Update task and its cfs_rq load average */
-static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
+static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
 {
-	u64 now = cfs_rq_clock_pelt(cfs_rq);
-	int decayed;
-
-	/*
-	 * Track task load average for carrying it to new CPU after migrated, and
-	 * track group sched_entity load average for task_h_load calculation in migration
-	 */
-	if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD))
-		__update_load_avg_se(now, cfs_rq, se);
-
-	decayed  = update_cfs_rq_load_avg(now, cfs_rq);
-	decayed |= propagate_entity_load_avg(se);
-
-	if (!se->avg.last_update_time && (flags & DO_ATTACH)) {
-
-		/*
-		 * DO_ATTACH means we're here from enqueue_entity().
-		 * !last_update_time means we've passed through
-		 * migrate_task_rq_fair() indicating we migrated.
-		 *
-		 * IOW we're enqueueing a task on a new CPU.
-		 */
-		attach_entity_load_avg(cfs_rq, se);
-		update_tg_load_avg(cfs_rq);
-
-	} else if (flags & DO_DETACH) {
-		/*
-		 * DO_DETACH means we're here from dequeue_entity()
-		 * and we are migrating task out of the CPU.
-		 */
-		detach_entity_load_avg(cfs_rq, se);
-		update_tg_load_avg(cfs_rq);
-	} else if (decayed) {
-		cfs_rq_util_change(cfs_rq, 0);
-
-		if (flags & UPDATE_TG)
-			update_tg_load_avg(cfs_rq);
-	}
+	return cfs_bandwidth_used() && cfs_rq->throttled;
 }
 
-/*
- * Synchronize entity load avg of dequeued entity without locking
- * the previous rq.
- */
-static void sync_entity_load_avg(struct sched_entity *se)
+/* check whether cfs_rq, or any parent, is throttled */
+static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
 {
-	struct cfs_rq *cfs_rq = cfs_rq_of(se);
-	u64 last_update_time;
-
-	last_update_time = cfs_rq_last_update_time(cfs_rq);
-	__update_load_avg_blocked_se(last_update_time, se);
+	return cfs_bandwidth_used() && cfs_rq->throttle_count;
 }
 
 /*
- * Task first catches up with cfs_rq, and then subtract
- * itself from the cfs_rq (task must be off the queue now).
+ * Ensure that neither of the group entities corresponding to src_cpu or
+ * dest_cpu are members of a throttled hierarchy when performing group
+ * load-balance operations.
  */
-static void remove_entity_load_avg(struct sched_entity *se)
+int throttled_lb_pair(struct task_group *tg, int src_cpu, int dest_cpu)
 {
-	struct cfs_rq *cfs_rq = cfs_rq_of(se);
-	unsigned long flags;
-
-	/*
-	 * tasks cannot exit without having gone through wake_up_new_task() ->
-	 * enqueue_task_fair() which will have added things to the cfs_rq,
-	 * so we can remove unconditionally.
-	 */
+	struct cfs_rq *src_cfs_rq, *dest_cfs_rq;
 
-	sync_entity_load_avg(se);
+	src_cfs_rq = tg->cfs_rq[src_cpu];
+	dest_cfs_rq = tg->cfs_rq[dest_cpu];
 
-	raw_spin_lock_irqsave(&cfs_rq->removed.lock, flags);
-	++cfs_rq->removed.nr;
-	cfs_rq->removed.util_avg	+= se->avg.util_avg;
-	cfs_rq->removed.load_avg	+= se->avg.load_avg;
-	cfs_rq->removed.runnable_avg	+= se->avg.runnable_avg;
-	raw_spin_unlock_irqrestore(&cfs_rq->removed.lock, flags);
+	return throttled_hierarchy(src_cfs_rq) ||
+	       throttled_hierarchy(dest_cfs_rq);
 }
 
-static inline unsigned long cfs_rq_runnable_avg(struct cfs_rq *cfs_rq)
+static int tg_unthrottle_up(struct task_group *tg, void *data)
 {
-	return cfs_rq->avg.runnable_avg;
-}
+	struct rq *rq = data;
+	struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
 
-static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq)
-{
-	return cfs_rq->avg.load_avg;
-}
+	cfs_rq->throttle_count--;
+	if (!cfs_rq->throttle_count) {
+		cfs_rq->throttled_clock_pelt_time += rq_clock_pelt(rq) -
+					     cfs_rq->throttled_clock_pelt;
 
-static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf);
+		/* Add cfs_rq with load or one or more already running entities to the list */
+		if (!cfs_rq_is_decayed(cfs_rq))
+			list_add_leaf_cfs_rq(cfs_rq);
 
-static inline unsigned long task_util(struct task_struct *p)
-{
-	return READ_ONCE(p->se.avg.util_avg);
-}
+		if (cfs_rq->throttled_clock_self) {
+			u64 delta = rq_clock(rq) - cfs_rq->throttled_clock_self;
 
-static inline unsigned long task_runnable(struct task_struct *p)
-{
-	return READ_ONCE(p->se.avg.runnable_avg);
-}
+			cfs_rq->throttled_clock_self = 0;
 
-static inline unsigned long _task_util_est(struct task_struct *p)
-{
-	return READ_ONCE(p->se.avg.util_est) & ~UTIL_AVG_UNCHANGED;
-}
+			if (SCHED_WARN_ON((s64)delta < 0))
+				delta = 0;
 
-static inline unsigned long task_util_est(struct task_struct *p)
-{
-	return max(task_util(p), _task_util_est(p));
+			cfs_rq->throttled_clock_self_time += delta;
+		}
+	}
+
+	return 0;
 }
 
-static inline void util_est_enqueue(struct cfs_rq *cfs_rq,
-				    struct task_struct *p)
+static int tg_throttle_down(struct task_group *tg, void *data)
 {
-	unsigned int enqueued;
+	struct rq *rq = data;
+	struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
 
-	if (!sched_feat(UTIL_EST))
-		return;
+	/* group is entering throttled state, stop time */
+	if (!cfs_rq->throttle_count) {
+		cfs_rq->throttled_clock_pelt = rq_clock_pelt(rq);
+		list_del_leaf_cfs_rq(cfs_rq);
 
-	/* Update root cfs_rq's estimated utilization */
-	enqueued  = cfs_rq->avg.util_est;
-	enqueued += _task_util_est(p);
-	WRITE_ONCE(cfs_rq->avg.util_est, enqueued);
+		SCHED_WARN_ON(cfs_rq->throttled_clock_self);
+		if (cfs_rq->nr_running)
+			cfs_rq->throttled_clock_self = rq_clock(rq);
+	}
+	cfs_rq->throttle_count++;
 
-	trace_sched_util_est_cfs_tp(cfs_rq);
+	return 0;
 }
 
-static inline void util_est_dequeue(struct cfs_rq *cfs_rq,
-				    struct task_struct *p)
+static bool throttle_cfs_rq(struct cfs_rq *cfs_rq)
 {
-	unsigned int enqueued;
+	struct rq *rq = rq_of(cfs_rq);
+	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+	struct sched_entity *se;
+	long task_delta, idle_task_delta, dequeue = 1;
 
-	if (!sched_feat(UTIL_EST))
-		return;
+	raw_spin_lock(&cfs_b->lock);
+	/* This will start the period timer if necessary */
+	if (__assign_cfs_rq_runtime(cfs_b, cfs_rq, 1)) {
+		/*
+		 * We have raced with bandwidth becoming available, and if we
+		 * actually throttled the timer might not unthrottle us for an
+		 * entire period. We additionally needed to make sure that any
+		 * subsequent check_cfs_rq_runtime calls agree not to throttle
+		 * us, as we may commit to do cfs put_prev+pick_next, so we ask
+		 * for 1ns of runtime rather than just check cfs_b.
+		 */
+		dequeue = 0;
+	} else {
+		list_add_tail_rcu(&cfs_rq->throttled_list,
+				  &cfs_b->throttled_cfs_rq);
+	}
+	raw_spin_unlock(&cfs_b->lock);
 
-	/* Update root cfs_rq's estimated utilization */
-	enqueued  = cfs_rq->avg.util_est;
-	enqueued -= min_t(unsigned int, enqueued, _task_util_est(p));
-	WRITE_ONCE(cfs_rq->avg.util_est, enqueued);
+	if (!dequeue)
+		return false;  /* Throttle no longer required. */
 
-	trace_sched_util_est_cfs_tp(cfs_rq);
-}
+	se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
 
-#define UTIL_EST_MARGIN (SCHED_CAPACITY_SCALE / 100)
+	/* freeze hierarchy runnable averages while throttled */
+	rcu_read_lock();
+	walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
+	rcu_read_unlock();
 
-static inline void util_est_update(struct cfs_rq *cfs_rq,
-				   struct task_struct *p,
-				   bool task_sleep)
-{
-	unsigned int ewma, dequeued, last_ewma_diff;
+	task_delta = cfs_rq->h_nr_running;
+	idle_task_delta = cfs_rq->idle_h_nr_running;
+	for_each_sched_entity(se) {
+		struct cfs_rq *qcfs_rq = cfs_rq_of(se);
+		/* throttled entity or throttle-on-deactivate */
+		if (!se->on_rq)
+			goto done;
 
-	if (!sched_feat(UTIL_EST))
-		return;
+		dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
 
-	/*
-	 * Skip update of task's estimated utilization when the task has not
-	 * yet completed an activation, e.g. being migrated.
-	 */
-	if (!task_sleep)
-		return;
+		if (cfs_rq_is_idle(group_cfs_rq(se)))
+			idle_task_delta = cfs_rq->h_nr_running;
 
-	/* Get current estimate of utilization */
-	ewma = READ_ONCE(p->se.avg.util_est);
+		qcfs_rq->h_nr_running -= task_delta;
+		qcfs_rq->idle_h_nr_running -= idle_task_delta;
 
-	/*
-	 * If the PELT values haven't changed since enqueue time,
-	 * skip the util_est update.
-	 */
-	if (ewma & UTIL_AVG_UNCHANGED)
-		return;
+		if (qcfs_rq->load.weight) {
+			/* Avoid re-evaluating load for this entity: */
+			se = parent_entity(se);
+			break;
+		}
+	}
 
-	/* Get utilization at dequeue */
-	dequeued = task_util(p);
+	for_each_sched_entity(se) {
+		struct cfs_rq *qcfs_rq = cfs_rq_of(se);
+		/* throttled entity or throttle-on-deactivate */
+		if (!se->on_rq)
+			goto done;
 
-	/*
-	 * Reset EWMA on utilization increases, the moving average is used only
-	 * to smooth utilization decreases.
-	 */
-	if (ewma <= dequeued) {
-		ewma = dequeued;
-		goto done;
+		update_load_avg(qcfs_rq, se, 0);
+		se_update_runnable(se);
+
+		if (cfs_rq_is_idle(group_cfs_rq(se)))
+			idle_task_delta = cfs_rq->h_nr_running;
+
+		qcfs_rq->h_nr_running -= task_delta;
+		qcfs_rq->idle_h_nr_running -= idle_task_delta;
 	}
 
-	/*
-	 * Skip update of task's estimated utilization when its members are
-	 * already ~1% close to its last activation value.
-	 */
-	last_ewma_diff = ewma - dequeued;
-	if (last_ewma_diff < UTIL_EST_MARGIN)
-		goto done;
+	/* At this point se is NULL and we are at root level*/
+	sub_nr_running(rq, task_delta);
 
+done:
 	/*
-	 * To avoid overestimation of actual task utilization, skip updates if
-	 * we cannot grant there is idle time in this CPU.
+	 * Note: distribution will already see us throttled via the
+	 * throttled-list.  rq->lock protects completion.
 	 */
-	if (dequeued > arch_scale_cpu_capacity(cpu_of(rq_of(cfs_rq))))
-		return;
+	cfs_rq->throttled = 1;
+	SCHED_WARN_ON(cfs_rq->throttled_clock);
+	if (cfs_rq->nr_running)
+		cfs_rq->throttled_clock = rq_clock(rq);
+	return true;
+}
 
-	/*
-	 * To avoid underestimate of task utilization, skip updates of EWMA if
-	 * we cannot grant that thread got all CPU time it wanted.
-	 */
-	if ((dequeued + UTIL_EST_MARGIN) < task_runnable(p))
-		goto done;
+void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
+{
+	struct rq *rq = rq_of(cfs_rq);
+	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+	struct sched_entity *se;
+	long task_delta, idle_task_delta;
 
+	se = cfs_rq->tg->se[cpu_of(rq)];
 
-	/*
-	 * Update Task's estimated utilization
-	 *
-	 * When *p completes an activation we can consolidate another sample
-	 * of the task size. This is done by using this value to update the
-	 * Exponential Weighted Moving Average (EWMA):
-	 *
-	 *  ewma(t) = w *  task_util(p) + (1-w) * ewma(t-1)
-	 *          = w *  task_util(p) +         ewma(t-1)  - w * ewma(t-1)
-	 *          = w * (task_util(p) -         ewma(t-1)) +     ewma(t-1)
-	 *          = w * (      -last_ewma_diff           ) +     ewma(t-1)
-	 *          = w * (-last_ewma_diff +  ewma(t-1) / w)
-	 *
-	 * Where 'w' is the weight of new samples, which is configured to be
-	 * 0.25, thus making w=1/4 ( >>= UTIL_EST_WEIGHT_SHIFT)
-	 */
-	ewma <<= UTIL_EST_WEIGHT_SHIFT;
-	ewma  -= last_ewma_diff;
-	ewma >>= UTIL_EST_WEIGHT_SHIFT;
-done:
-	ewma |= UTIL_AVG_UNCHANGED;
-	WRITE_ONCE(p->se.avg.util_est, ewma);
+	cfs_rq->throttled = 0;
 
-	trace_sched_util_est_se_tp(&p->se);
-}
+	update_rq_clock(rq);
 
-static inline int util_fits_cpu(unsigned long util,
-				unsigned long uclamp_min,
-				unsigned long uclamp_max,
-				int cpu)
-{
-	unsigned long capacity_orig, capacity_orig_thermal;
-	unsigned long capacity = capacity_of(cpu);
-	bool fits, uclamp_max_fits;
+	raw_spin_lock(&cfs_b->lock);
+	if (cfs_rq->throttled_clock) {
+		cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock;
+		cfs_rq->throttled_clock = 0;
+	}
+	list_del_rcu(&cfs_rq->throttled_list);
+	raw_spin_unlock(&cfs_b->lock);
 
-	/*
-	 * Check if the real util fits without any uclamp boost/cap applied.
-	 */
-	fits = fits_capacity(util, capacity);
+	/* update hierarchical throttle state */
+	walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
 
-	if (!uclamp_is_used())
-		return fits;
+	if (!cfs_rq->load.weight) {
+		if (!cfs_rq->on_list)
+			return;
+		/*
+		 * Nothing to run but something to decay (on_list)?
+		 * Complete the branch.
+		 */
+		for_each_sched_entity(se) {
+			if (list_add_leaf_cfs_rq(cfs_rq_of(se)))
+				break;
+		}
+		goto unthrottle_throttle;
+	}
 
-	/*
-	 * We must use arch_scale_cpu_capacity() for comparing against uclamp_min and
-	 * uclamp_max. We only care about capacity pressure (by using
-	 * capacity_of()) for comparing against the real util.
-	 *
-	 * If a task is boosted to 1024 for example, we don't want a tiny
-	 * pressure to skew the check whether it fits a CPU or not.
-	 *
-	 * Similarly if a task is capped to arch_scale_cpu_capacity(little_cpu), it
-	 * should fit a little cpu even if there's some pressure.
-	 *
-	 * Only exception is for thermal pressure since it has a direct impact
-	 * on available OPP of the system.
-	 *
-	 * We honour it for uclamp_min only as a drop in performance level
-	 * could result in not getting the requested minimum performance level.
-	 *
-	 * For uclamp_max, we can tolerate a drop in performance level as the
-	 * goal is to cap the task. So it's okay if it's getting less.
-	 */
-	capacity_orig = arch_scale_cpu_capacity(cpu);
-	capacity_orig_thermal = capacity_orig - arch_scale_thermal_pressure(cpu);
+	task_delta = cfs_rq->h_nr_running;
+	idle_task_delta = cfs_rq->idle_h_nr_running;
+	for_each_sched_entity(se) {
+		struct cfs_rq *qcfs_rq = cfs_rq_of(se);
 
-	/*
-	 * We want to force a task to fit a cpu as implied by uclamp_max.
-	 * But we do have some corner cases to cater for..
-	 *
-	 *
-	 *                                 C=z
-	 *   |                             ___
-	 *   |                  C=y       |   |
-	 *   |_ _ _ _ _ _ _ _ _ ___ _ _ _ | _ | _ _ _ _ _  uclamp_max
-	 *   |      C=x        |   |      |   |
-	 *   |      ___        |   |      |   |
-	 *   |     |   |       |   |      |   |    (util somewhere in this region)
-	 *   |     |   |       |   |      |   |
-	 *   |     |   |       |   |      |   |
-	 *   +----------------------------------------
-	 *         CPU0        CPU1       CPU2
-	 *
-	 *   In the above example if a task is capped to a specific performance
-	 *   point, y, then when:
-	 *
-	 *   * util = 80% of x then it does not fit on CPU0 and should migrate
-	 *     to CPU1
-	 *   * util = 80% of y then it is forced to fit on CPU1 to honour
-	 *     uclamp_max request.
-	 *
-	 *   which is what we're enforcing here. A task always fits if
-	 *   uclamp_max <= capacity_orig. But when uclamp_max > capacity_orig,
-	 *   the normal upmigration rules should withhold still.
-	 *
-	 *   Only exception is when we are on max capacity, then we need to be
-	 *   careful not to block overutilized state. This is so because:
-	 *
-	 *     1. There's no concept of capping at max_capacity! We can't go
-	 *        beyond this performance level anyway.
-	 *     2. The system is being saturated when we're operating near
-	 *        max capacity, it doesn't make sense to block overutilized.
-	 */
-	uclamp_max_fits = (capacity_orig == SCHED_CAPACITY_SCALE) && (uclamp_max == SCHED_CAPACITY_SCALE);
-	uclamp_max_fits = !uclamp_max_fits && (uclamp_max <= capacity_orig);
-	fits = fits || uclamp_max_fits;
+		if (se->on_rq)
+			break;
+		enqueue_entity(qcfs_rq, se, ENQUEUE_WAKEUP);
 
-	/*
-	 *
-	 *                                 C=z
-	 *   |                             ___       (region a, capped, util >= uclamp_max)
-	 *   |                  C=y       |   |
-	 *   |_ _ _ _ _ _ _ _ _ ___ _ _ _ | _ | _ _ _ _ _ uclamp_max
-	 *   |      C=x        |   |      |   |
-	 *   |      ___        |   |      |   |      (region b, uclamp_min <= util <= uclamp_max)
-	 *   |_ _ _|_ _|_ _ _ _| _ | _ _ _| _ | _ _ _ _ _ uclamp_min
-	 *   |     |   |       |   |      |   |
-	 *   |     |   |       |   |      |   |      (region c, boosted, util < uclamp_min)
-	 *   +----------------------------------------
-	 *         CPU0        CPU1       CPU2
-	 *
-	 * a) If util > uclamp_max, then we're capped, we don't care about
-	 *    actual fitness value here. We only care if uclamp_max fits
-	 *    capacity without taking margin/pressure into account.
-	 *    See comment above.
-	 *
-	 * b) If uclamp_min <= util <= uclamp_max, then the normal
-	 *    fits_capacity() rules apply. Except we need to ensure that we
-	 *    enforce we remain within uclamp_max, see comment above.
-	 *
-	 * c) If util < uclamp_min, then we are boosted. Same as (b) but we
-	 *    need to take into account the boosted value fits the CPU without
-	 *    taking margin/pressure into account.
-	 *
-	 * Cases (a) and (b) are handled in the 'fits' variable already. We
-	 * just need to consider an extra check for case (c) after ensuring we
-	 * handle the case uclamp_min > uclamp_max.
-	 */
-	uclamp_min = min(uclamp_min, uclamp_max);
-	if (fits && (util < uclamp_min) && (uclamp_min > capacity_orig_thermal))
-		return -1;
+		if (cfs_rq_is_idle(group_cfs_rq(se)))
+			idle_task_delta = cfs_rq->h_nr_running;
 
-	return fits;
-}
+		qcfs_rq->h_nr_running += task_delta;
+		qcfs_rq->idle_h_nr_running += idle_task_delta;
 
-static inline int task_fits_cpu(struct task_struct *p, int cpu)
-{
-	unsigned long uclamp_min = uclamp_eff_value(p, UCLAMP_MIN);
-	unsigned long uclamp_max = uclamp_eff_value(p, UCLAMP_MAX);
-	unsigned long util = task_util_est(p);
-	/*
-	 * Return true only if the cpu fully fits the task requirements, which
-	 * include the utilization but also the performance hints.
-	 */
-	return (util_fits_cpu(util, uclamp_min, uclamp_max, cpu) > 0);
+		/* end evaluation on encountering a throttled cfs_rq */
+		if (cfs_rq_throttled(qcfs_rq))
+			goto unthrottle_throttle;
+	}
+
+	for_each_sched_entity(se) {
+		struct cfs_rq *qcfs_rq = cfs_rq_of(se);
+
+		update_load_avg(qcfs_rq, se, UPDATE_TG);
+		se_update_runnable(se);
+
+		if (cfs_rq_is_idle(group_cfs_rq(se)))
+			idle_task_delta = cfs_rq->h_nr_running;
+
+		qcfs_rq->h_nr_running += task_delta;
+		qcfs_rq->idle_h_nr_running += idle_task_delta;
+
+		/* end evaluation on encountering a throttled cfs_rq */
+		if (cfs_rq_throttled(qcfs_rq))
+			goto unthrottle_throttle;
+	}
+
+	/* At this point se is NULL and we are at root level*/
+	add_nr_running(rq, task_delta);
+
+unthrottle_throttle:
+	assert_list_leaf_cfs_rq(rq);
+
+	/* Determine whether we need to wake up potentially idle CPU: */
+	if (rq->curr == rq->idle && rq->cfs.nr_running)
+		resched_curr(rq);
 }
 
-static inline void update_misfit_status(struct task_struct *p, struct rq *rq)
+#ifdef CONFIG_SMP
+static void __cfsb_csd_unthrottle(void *arg)
 {
-	int cpu = cpu_of(rq);
+	struct cfs_rq *cursor, *tmp;
+	struct rq *rq = arg;
+	struct rq_flags rf;
 
-	if (!sched_asym_cpucap_active())
-		return;
+	rq_lock(rq, &rf);
 
 	/*
-	 * Affinity allows us to go somewhere higher?  Or are we on biggest
-	 * available CPU already? Or do we fit into this CPU ?
+	 * Iterating over the list can trigger several call to
+	 * update_rq_clock() in unthrottle_cfs_rq().
+	 * Do it once and skip the potential next ones.
 	 */
-	if (!p || (p->nr_cpus_allowed == 1) ||
-	    (arch_scale_cpu_capacity(cpu) == p->max_allowed_capacity) ||
-	    task_fits_cpu(p, cpu)) {
-
-		rq->misfit_task_load = 0;
-		return;
-	}
+	update_rq_clock(rq);
+	rq_clock_start_loop_update(rq);
 
 	/*
-	 * Make sure that misfit_task_load will not be null even if
-	 * task_h_load() returns 0.
+	 * Since we hold rq lock we're safe from concurrent manipulation of
+	 * the CSD list. However, this RCU critical section annotates the
+	 * fact that we pair with sched_free_group_rcu(), so that we cannot
+	 * race with group being freed in the window between removing it
+	 * from the list and advancing to the next entry in the list.
 	 */
-	rq->misfit_task_load = max_t(unsigned long, task_h_load(p), 1);
-}
+	rcu_read_lock();
+
+	list_for_each_entry_safe(cursor, tmp, &rq->cfsb_csd_list,
+				 throttled_csd_list) {
+		list_del_init(&cursor->throttled_csd_list);
 
-#else /* CONFIG_SMP */
+		if (cfs_rq_throttled(cursor))
+			unthrottle_cfs_rq(cursor);
+	}
 
-static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
-{
-	return !cfs_rq->nr_running;
-}
+	rcu_read_unlock();
 
-#define UPDATE_TG	0x0
-#define SKIP_AGE_LOAD	0x0
-#define DO_ATTACH	0x0
-#define DO_DETACH	0x0
+	rq_clock_stop_loop_update(rq);
+	rq_unlock(rq, &rf);
+}
 
-static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int not_used1)
+static inline void __unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
 {
-	cfs_rq_util_change(cfs_rq, 0);
-}
+	struct rq *rq = rq_of(cfs_rq);
+	bool first;
 
-static inline void remove_entity_load_avg(struct sched_entity *se) {}
+	if (rq == this_rq()) {
+		unthrottle_cfs_rq(cfs_rq);
+		return;
+	}
 
-static inline void
-attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
-static inline void
-detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
+	/* Already enqueued */
+	if (SCHED_WARN_ON(!list_empty(&cfs_rq->throttled_csd_list)))
+		return;
 
-static inline int sched_balance_newidle(struct rq *rq, struct rq_flags *rf)
+	first = list_empty(&rq->cfsb_csd_list);
+	list_add_tail(&cfs_rq->throttled_csd_list, &rq->cfsb_csd_list);
+	if (first)
+		smp_call_function_single_async(cpu_of(rq), &rq->cfsb_csd);
+}
+#else
+static inline void __unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
 {
-	return 0;
+	unthrottle_cfs_rq(cfs_rq);
 }
+#endif
 
-static inline void
-util_est_enqueue(struct cfs_rq *cfs_rq, struct task_struct *p) {}
-
-static inline void
-util_est_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p) {}
+static void unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
+{
+	lockdep_assert_rq_held(rq_of(cfs_rq));
 
-static inline void
-util_est_update(struct cfs_rq *cfs_rq, struct task_struct *p,
-		bool task_sleep) {}
-static inline void update_misfit_status(struct task_struct *p, struct rq *rq) {}
+	if (SCHED_WARN_ON(!cfs_rq_throttled(cfs_rq) ||
+	    cfs_rq->runtime_remaining <= 0))
+		return;
 
-#endif /* CONFIG_SMP */
+	__unthrottle_cfs_rq_async(cfs_rq);
+}
 
-static void
-place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
+static bool distribute_cfs_runtime(struct cfs_bandwidth *cfs_b)
 {
-	u64 vslice, vruntime = avg_vruntime(cfs_rq);
-	s64 lag = 0;
+	int this_cpu = smp_processor_id();
+	u64 runtime, remaining = 1;
+	bool throttled = false;
+	struct cfs_rq *cfs_rq, *tmp;
+	struct rq_flags rf;
+	struct rq *rq;
+	LIST_HEAD(local_unthrottle);
 
-	se->slice = sysctl_sched_base_slice;
-	vslice = calc_delta_fair(se->slice, se);
+	rcu_read_lock();
+	list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq,
+				throttled_list) {
+		rq = rq_of(cfs_rq);
 
-	/*
-	 * Due to how V is constructed as the weighted average of entities,
-	 * adding tasks with positive lag, or removing tasks with negative lag
-	 * will move 'time' backwards, this can screw around with the lag of
-	 * other tasks.
-	 *
-	 * EEVDF: placement strategy #1 / #2
-	 */
-	if (sched_feat(PLACE_LAG) && cfs_rq->nr_running) {
-		struct sched_entity *curr = cfs_rq->curr;
-		unsigned long load;
-
-		lag = se->vlag;
-
-		/*
-		 * If we want to place a task and preserve lag, we have to
-		 * consider the effect of the new entity on the weighted
-		 * average and compensate for this, otherwise lag can quickly
-		 * evaporate.
-		 *
-		 * Lag is defined as:
-		 *
-		 *   lag_i = S - s_i = w_i * (V - v_i)
-		 *
-		 * To avoid the 'w_i' term all over the place, we only track
-		 * the virtual lag:
-		 *
-		 *   vl_i = V - v_i <=> v_i = V - vl_i
-		 *
-		 * And we take V to be the weighted average of all v:
-		 *
-		 *   V = (\Sum w_j*v_j) / W
-		 *
-		 * Where W is: \Sum w_j
-		 *
-		 * Then, the weighted average after adding an entity with lag
-		 * vl_i is given by:
-		 *
-		 *   V' = (\Sum w_j*v_j + w_i*v_i) / (W + w_i)
-		 *      = (W*V + w_i*(V - vl_i)) / (W + w_i)
-		 *      = (W*V + w_i*V - w_i*vl_i) / (W + w_i)
-		 *      = (V*(W + w_i) - w_i*l) / (W + w_i)
-		 *      = V - w_i*vl_i / (W + w_i)
-		 *
-		 * And the actual lag after adding an entity with vl_i is:
-		 *
-		 *   vl'_i = V' - v_i
-		 *         = V - w_i*vl_i / (W + w_i) - (V - vl_i)
-		 *         = vl_i - w_i*vl_i / (W + w_i)
-		 *
-		 * Which is strictly less than vl_i. So in order to preserve lag
-		 * we should inflate the lag before placement such that the
-		 * effective lag after placement comes out right.
-		 *
-		 * As such, invert the above relation for vl'_i to get the vl_i
-		 * we need to use such that the lag after placement is the lag
-		 * we computed before dequeue.
-		 *
-		 *   vl'_i = vl_i - w_i*vl_i / (W + w_i)
-		 *         = ((W + w_i)*vl_i - w_i*vl_i) / (W + w_i)
-		 *
-		 *   (W + w_i)*vl'_i = (W + w_i)*vl_i - w_i*vl_i
-		 *                   = W*vl_i
-		 *
-		 *   vl_i = (W + w_i)*vl'_i / W
-		 */
-		load = cfs_rq->avg_load;
-		if (curr && curr->on_rq)
-			load += scale_load_down(curr->load.weight);
-
-		lag *= load + scale_load_down(se->load.weight);
-		if (WARN_ON_ONCE(!load))
-			load = 1;
-		lag = div_s64(lag, load);
-	}
-
-	se->vruntime = vruntime - lag;
-
-	/*
-	 * When joining the competition; the existing tasks will be,
-	 * on average, halfway through their slice, as such start tasks
-	 * off with half a slice to ease into the competition.
-	 */
-	if (sched_feat(PLACE_DEADLINE_INITIAL) && (flags & ENQUEUE_INITIAL))
-		vslice /= 2;
-
-	/*
-	 * EEVDF: vd_i = ve_i + r_i/w_i
-	 */
-	se->deadline = se->vruntime + vslice;
-}
-
-static void check_enqueue_throttle(struct cfs_rq *cfs_rq);
-static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq);
-
-static inline bool cfs_bandwidth_used(void);
-
-static void
-enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
-{
-	bool curr = cfs_rq->curr == se;
-
-	/*
-	 * If we're the current task, we must renormalise before calling
-	 * update_curr().
-	 */
-	if (curr)
-		place_entity(cfs_rq, se, flags);
-
-	update_curr(cfs_rq);
-
-	/*
-	 * When enqueuing a sched_entity, we must:
-	 *   - Update loads to have both entity and cfs_rq synced with now.
-	 *   - For group_entity, update its runnable_weight to reflect the new
-	 *     h_nr_running of its group cfs_rq.
-	 *   - For group_entity, update its weight to reflect the new share of
-	 *     its group cfs_rq
-	 *   - Add its new weight to cfs_rq->load.weight
-	 */
-	update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
-	se_update_runnable(se);
-	/*
-	 * XXX update_load_avg() above will have attached us to the pelt sum;
-	 * but update_cfs_group() here will re-adjust the weight and have to
-	 * undo/redo all that. Seems wasteful.
-	 */
-	update_cfs_group(se);
-
-	/*
-	 * XXX now that the entity has been re-weighted, and it's lag adjusted,
-	 * we can place the entity.
-	 */
-	if (!curr)
-		place_entity(cfs_rq, se, flags);
-
-	account_entity_enqueue(cfs_rq, se);
-
-	/* Entity has migrated, no longer consider this task hot */
-	if (flags & ENQUEUE_MIGRATED)
-		se->exec_start = 0;
-
-	check_schedstat_required();
-	update_stats_enqueue_fair(cfs_rq, se, flags);
-	if (!curr)
-		__enqueue_entity(cfs_rq, se);
-	se->on_rq = 1;
-
-	if (cfs_rq->nr_running == 1) {
-		check_enqueue_throttle(cfs_rq);
-		if (!throttled_hierarchy(cfs_rq)) {
-			list_add_leaf_cfs_rq(cfs_rq);
-		} else {
-#ifdef CONFIG_CFS_BANDWIDTH
-			struct rq *rq = rq_of(cfs_rq);
-
-			if (cfs_rq_throttled(cfs_rq) && !cfs_rq->throttled_clock)
-				cfs_rq->throttled_clock = rq_clock(rq);
-			if (!cfs_rq->throttled_clock_self)
-				cfs_rq->throttled_clock_self = rq_clock(rq);
-#endif
-		}
-	}
-}
-
-static void __clear_buddies_next(struct sched_entity *se)
-{
-	for_each_sched_entity(se) {
-		struct cfs_rq *cfs_rq = cfs_rq_of(se);
-		if (cfs_rq->next != se)
-			break;
-
-		cfs_rq->next = NULL;
-	}
-}
-
-static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
-	if (cfs_rq->next == se)
-		__clear_buddies_next(se);
-}
-
-static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
-
-static void
-dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
-{
-	int action = UPDATE_TG;
-
-	if (entity_is_task(se) && task_on_rq_migrating(task_of(se)))
-		action |= DO_DETACH;
-
-	/*
-	 * Update run-time statistics of the 'current'.
-	 */
-	update_curr(cfs_rq);
-
-	/*
-	 * When dequeuing a sched_entity, we must:
-	 *   - Update loads to have both entity and cfs_rq synced with now.
-	 *   - For group_entity, update its runnable_weight to reflect the new
-	 *     h_nr_running of its group cfs_rq.
-	 *   - Subtract its previous weight from cfs_rq->load.weight.
-	 *   - For group entity, update its weight to reflect the new share
-	 *     of its group cfs_rq.
-	 */
-	update_load_avg(cfs_rq, se, action);
-	se_update_runnable(se);
-
-	update_stats_dequeue_fair(cfs_rq, se, flags);
-
-	clear_buddies(cfs_rq, se);
-
-	update_entity_lag(cfs_rq, se);
-	if (se != cfs_rq->curr)
-		__dequeue_entity(cfs_rq, se);
-	se->on_rq = 0;
-	account_entity_dequeue(cfs_rq, se);
-
-	/* return excess runtime on last dequeue */
-	return_cfs_rq_runtime(cfs_rq);
-
-	update_cfs_group(se);
-
-	/*
-	 * Now advance min_vruntime if @se was the entity holding it back,
-	 * except when: DEQUEUE_SAVE && !DEQUEUE_MOVE, in this case we'll be
-	 * put back on, and if we advance min_vruntime, we'll be placed back
-	 * further than we started -- i.e. we'll be penalized.
-	 */
-	if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) != DEQUEUE_SAVE)
-		update_min_vruntime(cfs_rq);
-
-	if (cfs_rq->nr_running == 0)
-		update_idle_cfs_rq_clock_pelt(cfs_rq);
-}
-
-static void
-set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
-	clear_buddies(cfs_rq, se);
-
-	/* 'current' is not kept within the tree. */
-	if (se->on_rq) {
-		/*
-		 * Any task has to be enqueued before it get to execute on
-		 * a CPU. So account for the time it spent waiting on the
-		 * runqueue.
-		 */
-		update_stats_wait_end_fair(cfs_rq, se);
-		__dequeue_entity(cfs_rq, se);
-		update_load_avg(cfs_rq, se, UPDATE_TG);
-		/*
-		 * HACK, stash a copy of deadline at the point of pick in vlag,
-		 * which isn't used until dequeue.
-		 */
-		se->vlag = se->deadline;
-	}
-
-	update_stats_curr_start(cfs_rq, se);
-	cfs_rq->curr = se;
-
-	/*
-	 * Track our maximum slice length, if the CPU's load is at
-	 * least twice that of our own weight (i.e. don't track it
-	 * when there are only lesser-weight tasks around):
-	 */
-	if (schedstat_enabled() &&
-	    rq_of(cfs_rq)->cfs.load.weight >= 2*se->load.weight) {
-		struct sched_statistics *stats;
-
-		stats = __schedstats_from_se(se);
-		__schedstat_set(stats->slice_max,
-				max((u64)stats->slice_max,
-				    se->sum_exec_runtime - se->prev_sum_exec_runtime));
-	}
-
-	se->prev_sum_exec_runtime = se->sum_exec_runtime;
-}
-
-/*
- * Pick the next process, keeping these things in mind, in this order:
- * 1) keep things fair between processes/task groups
- * 2) pick the "next" process, since someone really wants that to run
- * 3) pick the "last" process, for cache locality
- * 4) do not run the "skip" process, if something else is available
- */
-static struct sched_entity *
-pick_next_entity(struct cfs_rq *cfs_rq)
-{
-	/*
-	 * Enabling NEXT_BUDDY will affect latency but not fairness.
-	 */
-	if (sched_feat(NEXT_BUDDY) &&
-	    cfs_rq->next && entity_eligible(cfs_rq, cfs_rq->next))
-		return cfs_rq->next;
-
-	return pick_eevdf(cfs_rq);
-}
-
-static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
-
-static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
-{
-	/*
-	 * If still on the runqueue then deactivate_task()
-	 * was not called and update_curr() has to be done:
-	 */
-	if (prev->on_rq)
-		update_curr(cfs_rq);
-
-	/* throttle cfs_rqs exceeding runtime */
-	check_cfs_rq_runtime(cfs_rq);
-
-	if (prev->on_rq) {
-		update_stats_wait_start_fair(cfs_rq, prev);
-		/* Put 'current' back into the tree. */
-		__enqueue_entity(cfs_rq, prev);
-		/* in !on_rq case, update occurred at dequeue */
-		update_load_avg(cfs_rq, prev, 0);
-	}
-	cfs_rq->curr = NULL;
-}
-
-static void
-entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
-{
-	/*
-	 * Update run-time statistics of the 'current'.
-	 */
-	update_curr(cfs_rq);
-
-	/*
-	 * Ensure that runnable average is periodically updated.
-	 */
-	update_load_avg(cfs_rq, curr, UPDATE_TG);
-	update_cfs_group(curr);
-
-#ifdef CONFIG_SCHED_HRTICK
-	/*
-	 * queued ticks are scheduled to match the slice, so don't bother
-	 * validating it and just reschedule.
-	 */
-	if (queued) {
-		resched_curr(rq_of(cfs_rq));
-		return;
-	}
-	/*
-	 * don't let the period tick interfere with the hrtick preemption
-	 */
-	if (!sched_feat(DOUBLE_TICK) &&
-			hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
-		return;
-#endif
-}
-
-
-/**************************************************
- * CFS bandwidth control machinery
- */
-
-#ifdef CONFIG_CFS_BANDWIDTH
-
-#ifdef CONFIG_JUMP_LABEL
-static struct static_key __cfs_bandwidth_used;
-
-static inline bool cfs_bandwidth_used(void)
-{
-	return static_key_false(&__cfs_bandwidth_used);
-}
-
-void cfs_bandwidth_usage_inc(void)
-{
-	static_key_slow_inc_cpuslocked(&__cfs_bandwidth_used);
-}
-
-void cfs_bandwidth_usage_dec(void)
-{
-	static_key_slow_dec_cpuslocked(&__cfs_bandwidth_used);
-}
-#else /* CONFIG_JUMP_LABEL */
-static bool cfs_bandwidth_used(void)
-{
-	return true;
-}
-
-void cfs_bandwidth_usage_inc(void) {}
-void cfs_bandwidth_usage_dec(void) {}
-#endif /* CONFIG_JUMP_LABEL */
-
-/*
- * default period for cfs group bandwidth.
- * default: 0.1s, units: nanoseconds
- */
-static inline u64 default_cfs_period(void)
-{
-	return 100000000ULL;
-}
-
-static inline u64 sched_cfs_bandwidth_slice(void)
-{
-	return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
-}
-
-/*
- * Replenish runtime according to assigned quota. We use sched_clock_cpu
- * directly instead of rq->clock to avoid adding additional synchronization
- * around rq->lock.
- *
- * requires cfs_b->lock
- */
-void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
-{
-	s64 runtime;
-
-	if (unlikely(cfs_b->quota == RUNTIME_INF))
-		return;
-
-	cfs_b->runtime += cfs_b->quota;
-	runtime = cfs_b->runtime_snap - cfs_b->runtime;
-	if (runtime > 0) {
-		cfs_b->burst_time += runtime;
-		cfs_b->nr_burst++;
-	}
-
-	cfs_b->runtime = min(cfs_b->runtime, cfs_b->quota + cfs_b->burst);
-	cfs_b->runtime_snap = cfs_b->runtime;
-}
-
-static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
-{
-	return &tg->cfs_bandwidth;
-}
-
-/* returns 0 on failure to allocate runtime */
-static int __assign_cfs_rq_runtime(struct cfs_bandwidth *cfs_b,
-				   struct cfs_rq *cfs_rq, u64 target_runtime)
-{
-	u64 min_amount, amount = 0;
-
-	lockdep_assert_held(&cfs_b->lock);
-
-	/* note: this is a positive sum as runtime_remaining <= 0 */
-	min_amount = target_runtime - cfs_rq->runtime_remaining;
-
-	if (cfs_b->quota == RUNTIME_INF)
-		amount = min_amount;
-	else {
-		start_cfs_bandwidth(cfs_b);
-
-		if (cfs_b->runtime > 0) {
-			amount = min(cfs_b->runtime, min_amount);
-			cfs_b->runtime -= amount;
-			cfs_b->idle = 0;
-		}
-	}
-
-	cfs_rq->runtime_remaining += amount;
-
-	return cfs_rq->runtime_remaining > 0;
-}
-
-/* returns 0 on failure to allocate runtime */
-static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
-{
-	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
-	int ret;
-
-	raw_spin_lock(&cfs_b->lock);
-	ret = __assign_cfs_rq_runtime(cfs_b, cfs_rq, sched_cfs_bandwidth_slice());
-	raw_spin_unlock(&cfs_b->lock);
-
-	return ret;
-}
-
-static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
-{
-	/* dock delta_exec before expiring quota (as it could span periods) */
-	cfs_rq->runtime_remaining -= delta_exec;
-
-	if (likely(cfs_rq->runtime_remaining > 0))
-		return;
-
-	if (cfs_rq->throttled)
-		return;
-	/*
-	 * if we're unable to extend our runtime we resched so that the active
-	 * hierarchy can be throttled
-	 */
-	if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
-		resched_curr(rq_of(cfs_rq));
-}
-
-static __always_inline
-void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
-{
-	if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled)
-		return;
-
-	__account_cfs_rq_runtime(cfs_rq, delta_exec);
-}
-
-static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
-{
-	return cfs_bandwidth_used() && cfs_rq->throttled;
-}
-
-/* check whether cfs_rq, or any parent, is throttled */
-static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
-{
-	return cfs_bandwidth_used() && cfs_rq->throttle_count;
-}
-
-/*
- * Ensure that neither of the group entities corresponding to src_cpu or
- * dest_cpu are members of a throttled hierarchy when performing group
- * load-balance operations.
- */
-static inline int throttled_lb_pair(struct task_group *tg,
-				    int src_cpu, int dest_cpu)
-{
-	struct cfs_rq *src_cfs_rq, *dest_cfs_rq;
-
-	src_cfs_rq = tg->cfs_rq[src_cpu];
-	dest_cfs_rq = tg->cfs_rq[dest_cpu];
-
-	return throttled_hierarchy(src_cfs_rq) ||
-	       throttled_hierarchy(dest_cfs_rq);
-}
-
-static int tg_unthrottle_up(struct task_group *tg, void *data)
-{
-	struct rq *rq = data;
-	struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
-
-	cfs_rq->throttle_count--;
-	if (!cfs_rq->throttle_count) {
-		cfs_rq->throttled_clock_pelt_time += rq_clock_pelt(rq) -
-					     cfs_rq->throttled_clock_pelt;
-
-		/* Add cfs_rq with load or one or more already running entities to the list */
-		if (!cfs_rq_is_decayed(cfs_rq))
-			list_add_leaf_cfs_rq(cfs_rq);
-
-		if (cfs_rq->throttled_clock_self) {
-			u64 delta = rq_clock(rq) - cfs_rq->throttled_clock_self;
-
-			cfs_rq->throttled_clock_self = 0;
-
-			if (SCHED_WARN_ON((s64)delta < 0))
-				delta = 0;
-
-			cfs_rq->throttled_clock_self_time += delta;
-		}
-	}
-
-	return 0;
-}
-
-static int tg_throttle_down(struct task_group *tg, void *data)
-{
-	struct rq *rq = data;
-	struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
-
-	/* group is entering throttled state, stop time */
-	if (!cfs_rq->throttle_count) {
-		cfs_rq->throttled_clock_pelt = rq_clock_pelt(rq);
-		list_del_leaf_cfs_rq(cfs_rq);
-
-		SCHED_WARN_ON(cfs_rq->throttled_clock_self);
-		if (cfs_rq->nr_running)
-			cfs_rq->throttled_clock_self = rq_clock(rq);
-	}
-	cfs_rq->throttle_count++;
-
-	return 0;
-}
-
-static bool throttle_cfs_rq(struct cfs_rq *cfs_rq)
-{
-	struct rq *rq = rq_of(cfs_rq);
-	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
-	struct sched_entity *se;
-	long task_delta, idle_task_delta, dequeue = 1;
-
-	raw_spin_lock(&cfs_b->lock);
-	/* This will start the period timer if necessary */
-	if (__assign_cfs_rq_runtime(cfs_b, cfs_rq, 1)) {
-		/*
-		 * We have raced with bandwidth becoming available, and if we
-		 * actually throttled the timer might not unthrottle us for an
-		 * entire period. We additionally needed to make sure that any
-		 * subsequent check_cfs_rq_runtime calls agree not to throttle
-		 * us, as we may commit to do cfs put_prev+pick_next, so we ask
-		 * for 1ns of runtime rather than just check cfs_b.
-		 */
-		dequeue = 0;
-	} else {
-		list_add_tail_rcu(&cfs_rq->throttled_list,
-				  &cfs_b->throttled_cfs_rq);
-	}
-	raw_spin_unlock(&cfs_b->lock);
-
-	if (!dequeue)
-		return false;  /* Throttle no longer required. */
-
-	se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
-
-	/* freeze hierarchy runnable averages while throttled */
-	rcu_read_lock();
-	walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
-	rcu_read_unlock();
-
-	task_delta = cfs_rq->h_nr_running;
-	idle_task_delta = cfs_rq->idle_h_nr_running;
-	for_each_sched_entity(se) {
-		struct cfs_rq *qcfs_rq = cfs_rq_of(se);
-		/* throttled entity or throttle-on-deactivate */
-		if (!se->on_rq)
-			goto done;
-
-		dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
-
-		if (cfs_rq_is_idle(group_cfs_rq(se)))
-			idle_task_delta = cfs_rq->h_nr_running;
-
-		qcfs_rq->h_nr_running -= task_delta;
-		qcfs_rq->idle_h_nr_running -= idle_task_delta;
-
-		if (qcfs_rq->load.weight) {
-			/* Avoid re-evaluating load for this entity: */
-			se = parent_entity(se);
-			break;
-		}
-	}
-
-	for_each_sched_entity(se) {
-		struct cfs_rq *qcfs_rq = cfs_rq_of(se);
-		/* throttled entity or throttle-on-deactivate */
-		if (!se->on_rq)
-			goto done;
-
-		update_load_avg(qcfs_rq, se, 0);
-		se_update_runnable(se);
-
-		if (cfs_rq_is_idle(group_cfs_rq(se)))
-			idle_task_delta = cfs_rq->h_nr_running;
-
-		qcfs_rq->h_nr_running -= task_delta;
-		qcfs_rq->idle_h_nr_running -= idle_task_delta;
-	}
-
-	/* At this point se is NULL and we are at root level*/
-	sub_nr_running(rq, task_delta);
-
-done:
-	/*
-	 * Note: distribution will already see us throttled via the
-	 * throttled-list.  rq->lock protects completion.
-	 */
-	cfs_rq->throttled = 1;
-	SCHED_WARN_ON(cfs_rq->throttled_clock);
-	if (cfs_rq->nr_running)
-		cfs_rq->throttled_clock = rq_clock(rq);
-	return true;
-}
-
-void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
-{
-	struct rq *rq = rq_of(cfs_rq);
-	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
-	struct sched_entity *se;
-	long task_delta, idle_task_delta;
-
-	se = cfs_rq->tg->se[cpu_of(rq)];
-
-	cfs_rq->throttled = 0;
-
-	update_rq_clock(rq);
-
-	raw_spin_lock(&cfs_b->lock);
-	if (cfs_rq->throttled_clock) {
-		cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock;
-		cfs_rq->throttled_clock = 0;
-	}
-	list_del_rcu(&cfs_rq->throttled_list);
-	raw_spin_unlock(&cfs_b->lock);
-
-	/* update hierarchical throttle state */
-	walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
-
-	if (!cfs_rq->load.weight) {
-		if (!cfs_rq->on_list)
-			return;
-		/*
-		 * Nothing to run but something to decay (on_list)?
-		 * Complete the branch.
-		 */
-		for_each_sched_entity(se) {
-			if (list_add_leaf_cfs_rq(cfs_rq_of(se)))
-				break;
-		}
-		goto unthrottle_throttle;
-	}
-
-	task_delta = cfs_rq->h_nr_running;
-	idle_task_delta = cfs_rq->idle_h_nr_running;
-	for_each_sched_entity(se) {
-		struct cfs_rq *qcfs_rq = cfs_rq_of(se);
-
-		if (se->on_rq)
-			break;
-		enqueue_entity(qcfs_rq, se, ENQUEUE_WAKEUP);
-
-		if (cfs_rq_is_idle(group_cfs_rq(se)))
-			idle_task_delta = cfs_rq->h_nr_running;
-
-		qcfs_rq->h_nr_running += task_delta;
-		qcfs_rq->idle_h_nr_running += idle_task_delta;
-
-		/* end evaluation on encountering a throttled cfs_rq */
-		if (cfs_rq_throttled(qcfs_rq))
-			goto unthrottle_throttle;
-	}
-
-	for_each_sched_entity(se) {
-		struct cfs_rq *qcfs_rq = cfs_rq_of(se);
-
-		update_load_avg(qcfs_rq, se, UPDATE_TG);
-		se_update_runnable(se);
-
-		if (cfs_rq_is_idle(group_cfs_rq(se)))
-			idle_task_delta = cfs_rq->h_nr_running;
-
-		qcfs_rq->h_nr_running += task_delta;
-		qcfs_rq->idle_h_nr_running += idle_task_delta;
-
-		/* end evaluation on encountering a throttled cfs_rq */
-		if (cfs_rq_throttled(qcfs_rq))
-			goto unthrottle_throttle;
-	}
-
-	/* At this point se is NULL and we are at root level*/
-	add_nr_running(rq, task_delta);
-
-unthrottle_throttle:
-	assert_list_leaf_cfs_rq(rq);
-
-	/* Determine whether we need to wake up potentially idle CPU: */
-	if (rq->curr == rq->idle && rq->cfs.nr_running)
-		resched_curr(rq);
-}
-
-#ifdef CONFIG_SMP
-static void __cfsb_csd_unthrottle(void *arg)
-{
-	struct cfs_rq *cursor, *tmp;
-	struct rq *rq = arg;
-	struct rq_flags rf;
-
-	rq_lock(rq, &rf);
-
-	/*
-	 * Iterating over the list can trigger several call to
-	 * update_rq_clock() in unthrottle_cfs_rq().
-	 * Do it once and skip the potential next ones.
-	 */
-	update_rq_clock(rq);
-	rq_clock_start_loop_update(rq);
-
-	/*
-	 * Since we hold rq lock we're safe from concurrent manipulation of
-	 * the CSD list. However, this RCU critical section annotates the
-	 * fact that we pair with sched_free_group_rcu(), so that we cannot
-	 * race with group being freed in the window between removing it
-	 * from the list and advancing to the next entry in the list.
-	 */
-	rcu_read_lock();
-
-	list_for_each_entry_safe(cursor, tmp, &rq->cfsb_csd_list,
-				 throttled_csd_list) {
-		list_del_init(&cursor->throttled_csd_list);
-
-		if (cfs_rq_throttled(cursor))
-			unthrottle_cfs_rq(cursor);
-	}
-
-	rcu_read_unlock();
-
-	rq_clock_stop_loop_update(rq);
-	rq_unlock(rq, &rf);
-}
-
-static inline void __unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
-{
-	struct rq *rq = rq_of(cfs_rq);
-	bool first;
-
-	if (rq == this_rq()) {
-		unthrottle_cfs_rq(cfs_rq);
-		return;
-	}
-
-	/* Already enqueued */
-	if (SCHED_WARN_ON(!list_empty(&cfs_rq->throttled_csd_list)))
-		return;
-
-	first = list_empty(&rq->cfsb_csd_list);
-	list_add_tail(&cfs_rq->throttled_csd_list, &rq->cfsb_csd_list);
-	if (first)
-		smp_call_function_single_async(cpu_of(rq), &rq->cfsb_csd);
-}
-#else
-static inline void __unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
-{
-	unthrottle_cfs_rq(cfs_rq);
-}
-#endif
-
-static void unthrottle_cfs_rq_async(struct cfs_rq *cfs_rq)
-{
-	lockdep_assert_rq_held(rq_of(cfs_rq));
-
-	if (SCHED_WARN_ON(!cfs_rq_throttled(cfs_rq) ||
-	    cfs_rq->runtime_remaining <= 0))
-		return;
-
-	__unthrottle_cfs_rq_async(cfs_rq);
-}
-
-static bool distribute_cfs_runtime(struct cfs_bandwidth *cfs_b)
-{
-	int this_cpu = smp_processor_id();
-	u64 runtime, remaining = 1;
-	bool throttled = false;
-	struct cfs_rq *cfs_rq, *tmp;
-	struct rq_flags rf;
-	struct rq *rq;
-	LIST_HEAD(local_unthrottle);
-
-	rcu_read_lock();
-	list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq,
-				throttled_list) {
-		rq = rq_of(cfs_rq);
-
-		if (!remaining) {
-			throttled = true;
-			break;
-		}
-
-		rq_lock_irqsave(rq, &rf);
-		if (!cfs_rq_throttled(cfs_rq))
-			goto next;
-
-		/* Already queued for async unthrottle */
-		if (!list_empty(&cfs_rq->throttled_csd_list))
-			goto next;
-
-		/* By the above checks, this should never be true */
-		SCHED_WARN_ON(cfs_rq->runtime_remaining > 0);
-
-		raw_spin_lock(&cfs_b->lock);
-		runtime = -cfs_rq->runtime_remaining + 1;
-		if (runtime > cfs_b->runtime)
-			runtime = cfs_b->runtime;
-		cfs_b->runtime -= runtime;
-		remaining = cfs_b->runtime;
-		raw_spin_unlock(&cfs_b->lock);
-
-		cfs_rq->runtime_remaining += runtime;
-
-		/* we check whether we're throttled above */
-		if (cfs_rq->runtime_remaining > 0) {
-			if (cpu_of(rq) != this_cpu) {
-				unthrottle_cfs_rq_async(cfs_rq);
-			} else {
-				/*
-				 * We currently only expect to be unthrottling
-				 * a single cfs_rq locally.
-				 */
-				SCHED_WARN_ON(!list_empty(&local_unthrottle));
-				list_add_tail(&cfs_rq->throttled_csd_list,
-					      &local_unthrottle);
-			}
-		} else {
-			throttled = true;
-		}
-
-next:
-		rq_unlock_irqrestore(rq, &rf);
-	}
-
-	list_for_each_entry_safe(cfs_rq, tmp, &local_unthrottle,
-				 throttled_csd_list) {
-		struct rq *rq = rq_of(cfs_rq);
-
-		rq_lock_irqsave(rq, &rf);
-
-		list_del_init(&cfs_rq->throttled_csd_list);
-
-		if (cfs_rq_throttled(cfs_rq))
-			unthrottle_cfs_rq(cfs_rq);
-
-		rq_unlock_irqrestore(rq, &rf);
-	}
-	SCHED_WARN_ON(!list_empty(&local_unthrottle));
-
-	rcu_read_unlock();
-
-	return throttled;
-}
-
-/*
- * Responsible for refilling a task_group's bandwidth and unthrottling its
- * cfs_rqs as appropriate. If there has been no activity within the last
- * period the timer is deactivated until scheduling resumes; cfs_b->idle is
- * used to track this state.
- */
-static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun, unsigned long flags)
-{
-	int throttled;
-
-	/* no need to continue the timer with no bandwidth constraint */
-	if (cfs_b->quota == RUNTIME_INF)
-		goto out_deactivate;
-
-	throttled = !list_empty(&cfs_b->throttled_cfs_rq);
-	cfs_b->nr_periods += overrun;
-
-	/* Refill extra burst quota even if cfs_b->idle */
-	__refill_cfs_bandwidth_runtime(cfs_b);
-
-	/*
-	 * idle depends on !throttled (for the case of a large deficit), and if
-	 * we're going inactive then everything else can be deferred
-	 */
-	if (cfs_b->idle && !throttled)
-		goto out_deactivate;
-
-	if (!throttled) {
-		/* mark as potentially idle for the upcoming period */
-		cfs_b->idle = 1;
-		return 0;
-	}
-
-	/* account preceding periods in which throttling occurred */
-	cfs_b->nr_throttled += overrun;
-
-	/*
-	 * This check is repeated as we release cfs_b->lock while we unthrottle.
-	 */
-	while (throttled && cfs_b->runtime > 0) {
-		raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
-		/* we can't nest cfs_b->lock while distributing bandwidth */
-		throttled = distribute_cfs_runtime(cfs_b);
-		raw_spin_lock_irqsave(&cfs_b->lock, flags);
-	}
-
-	/*
-	 * While we are ensured activity in the period following an
-	 * unthrottle, this also covers the case in which the new bandwidth is
-	 * insufficient to cover the existing bandwidth deficit.  (Forcing the
-	 * timer to remain active while there are any throttled entities.)
-	 */
-	cfs_b->idle = 0;
-
-	return 0;
-
-out_deactivate:
-	return 1;
-}
-
-/* a cfs_rq won't donate quota below this amount */
-static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC;
-/* minimum remaining period time to redistribute slack quota */
-static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC;
-/* how long we wait to gather additional slack before distributing */
-static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC;
-
-/*
- * Are we near the end of the current quota period?
- *
- * Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the
- * hrtimer base being cleared by hrtimer_start. In the case of
- * migrate_hrtimers, base is never cleared, so we are fine.
- */
-static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
-{
-	struct hrtimer *refresh_timer = &cfs_b->period_timer;
-	s64 remaining;
-
-	/* if the call-back is running a quota refresh is already occurring */
-	if (hrtimer_callback_running(refresh_timer))
-		return 1;
-
-	/* is a quota refresh about to occur? */
-	remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
-	if (remaining < (s64)min_expire)
-		return 1;
-
-	return 0;
-}
-
-static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b)
-{
-	u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration;
-
-	/* if there's a quota refresh soon don't bother with slack */
-	if (runtime_refresh_within(cfs_b, min_left))
-		return;
-
-	/* don't push forwards an existing deferred unthrottle */
-	if (cfs_b->slack_started)
-		return;
-	cfs_b->slack_started = true;
-
-	hrtimer_start(&cfs_b->slack_timer,
-			ns_to_ktime(cfs_bandwidth_slack_period),
-			HRTIMER_MODE_REL);
-}
-
-/* we know any runtime found here is valid as update_curr() precedes return */
-static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
-{
-	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
-	s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime;
-
-	if (slack_runtime <= 0)
-		return;
-
-	raw_spin_lock(&cfs_b->lock);
-	if (cfs_b->quota != RUNTIME_INF) {
-		cfs_b->runtime += slack_runtime;
-
-		/* we are under rq->lock, defer unthrottling using a timer */
-		if (cfs_b->runtime > sched_cfs_bandwidth_slice() &&
-		    !list_empty(&cfs_b->throttled_cfs_rq))
-			start_cfs_slack_bandwidth(cfs_b);
-	}
-	raw_spin_unlock(&cfs_b->lock);
-
-	/* even if it's not valid for return we don't want to try again */
-	cfs_rq->runtime_remaining -= slack_runtime;
-}
-
-static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
-{
-	if (!cfs_bandwidth_used())
-		return;
-
-	if (!cfs_rq->runtime_enabled || cfs_rq->nr_running)
-		return;
-
-	__return_cfs_rq_runtime(cfs_rq);
-}
-
-/*
- * This is done with a timer (instead of inline with bandwidth return) since
- * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
- */
-static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
-{
-	u64 runtime = 0, slice = sched_cfs_bandwidth_slice();
-	unsigned long flags;
-
-	/* confirm we're still not at a refresh boundary */
-	raw_spin_lock_irqsave(&cfs_b->lock, flags);
-	cfs_b->slack_started = false;
-
-	if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) {
-		raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
-		return;
-	}
-
-	if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice)
-		runtime = cfs_b->runtime;
-
-	raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
-
-	if (!runtime)
-		return;
-
-	distribute_cfs_runtime(cfs_b);
-}
-
-/*
- * When a group wakes up we want to make sure that its quota is not already
- * expired/exceeded, otherwise it may be allowed to steal additional ticks of
- * runtime as update_curr() throttling can not trigger until it's on-rq.
- */
-static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
-{
-	if (!cfs_bandwidth_used())
-		return;
-
-	/* an active group must be handled by the update_curr()->put() path */
-	if (!cfs_rq->runtime_enabled || cfs_rq->curr)
-		return;
-
-	/* ensure the group is not already throttled */
-	if (cfs_rq_throttled(cfs_rq))
-		return;
-
-	/* update runtime allocation */
-	account_cfs_rq_runtime(cfs_rq, 0);
-	if (cfs_rq->runtime_remaining <= 0)
-		throttle_cfs_rq(cfs_rq);
-}
-
-static void sync_throttle(struct task_group *tg, int cpu)
-{
-	struct cfs_rq *pcfs_rq, *cfs_rq;
-
-	if (!cfs_bandwidth_used())
-		return;
-
-	if (!tg->parent)
-		return;
-
-	cfs_rq = tg->cfs_rq[cpu];
-	pcfs_rq = tg->parent->cfs_rq[cpu];
-
-	cfs_rq->throttle_count = pcfs_rq->throttle_count;
-	cfs_rq->throttled_clock_pelt = rq_clock_pelt(cpu_rq(cpu));
-}
-
-/* conditionally throttle active cfs_rq's from put_prev_entity() */
-static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq)
-{
-	if (!cfs_bandwidth_used())
-		return false;
-
-	if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0))
-		return false;
-
-	/*
-	 * it's possible for a throttled entity to be forced into a running
-	 * state (e.g. set_curr_task), in this case we're finished.
-	 */
-	if (cfs_rq_throttled(cfs_rq))
-		return true;
-
-	return throttle_cfs_rq(cfs_rq);
-}
-
-static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer)
-{
-	struct cfs_bandwidth *cfs_b =
-		container_of(timer, struct cfs_bandwidth, slack_timer);
-
-	do_sched_cfs_slack_timer(cfs_b);
-
-	return HRTIMER_NORESTART;
-}
-
-extern const u64 max_cfs_quota_period;
-
-static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)
-{
-	struct cfs_bandwidth *cfs_b =
-		container_of(timer, struct cfs_bandwidth, period_timer);
-	unsigned long flags;
-	int overrun;
-	int idle = 0;
-	int count = 0;
-
-	raw_spin_lock_irqsave(&cfs_b->lock, flags);
-	for (;;) {
-		overrun = hrtimer_forward_now(timer, cfs_b->period);
-		if (!overrun)
-			break;
-
-		idle = do_sched_cfs_period_timer(cfs_b, overrun, flags);
-
-		if (++count > 3) {
-			u64 new, old = ktime_to_ns(cfs_b->period);
-
-			/*
-			 * Grow period by a factor of 2 to avoid losing precision.
-			 * Precision loss in the quota/period ratio can cause __cfs_schedulable
-			 * to fail.
-			 */
-			new = old * 2;
-			if (new < max_cfs_quota_period) {
-				cfs_b->period = ns_to_ktime(new);
-				cfs_b->quota *= 2;
-				cfs_b->burst *= 2;
-
-				pr_warn_ratelimited(
-	"cfs_period_timer[cpu%d]: period too short, scaling up (new cfs_period_us = %lld, cfs_quota_us = %lld)\n",
-					smp_processor_id(),
-					div_u64(new, NSEC_PER_USEC),
-					div_u64(cfs_b->quota, NSEC_PER_USEC));
-			} else {
-				pr_warn_ratelimited(
-	"cfs_period_timer[cpu%d]: period too short, but cannot scale up without losing precision (cfs_period_us = %lld, cfs_quota_us = %lld)\n",
-					smp_processor_id(),
-					div_u64(old, NSEC_PER_USEC),
-					div_u64(cfs_b->quota, NSEC_PER_USEC));
-			}
-
-			/* reset count so we don't come right back in here */
-			count = 0;
-		}
-	}
-	if (idle)
-		cfs_b->period_active = 0;
-	raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
-
-	return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
-}
-
-void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b, struct cfs_bandwidth *parent)
-{
-	raw_spin_lock_init(&cfs_b->lock);
-	cfs_b->runtime = 0;
-	cfs_b->quota = RUNTIME_INF;
-	cfs_b->period = ns_to_ktime(default_cfs_period());
-	cfs_b->burst = 0;
-	cfs_b->hierarchical_quota = parent ? parent->hierarchical_quota : RUNTIME_INF;
-
-	INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
-	hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED);
-	cfs_b->period_timer.function = sched_cfs_period_timer;
-
-	/* Add a random offset so that timers interleave */
-	hrtimer_set_expires(&cfs_b->period_timer,
-			    get_random_u32_below(cfs_b->period));
-	hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
-	cfs_b->slack_timer.function = sched_cfs_slack_timer;
-	cfs_b->slack_started = false;
-}
-
-static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
-{
-	cfs_rq->runtime_enabled = 0;
-	INIT_LIST_HEAD(&cfs_rq->throttled_list);
-	INIT_LIST_HEAD(&cfs_rq->throttled_csd_list);
-}
-
-void start_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
-{
-	lockdep_assert_held(&cfs_b->lock);
-
-	if (cfs_b->period_active)
-		return;
-
-	cfs_b->period_active = 1;
-	hrtimer_forward_now(&cfs_b->period_timer, cfs_b->period);
-	hrtimer_start_expires(&cfs_b->period_timer, HRTIMER_MODE_ABS_PINNED);
-}
-
-static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
-{
-	int __maybe_unused i;
-
-	/* init_cfs_bandwidth() was not called */
-	if (!cfs_b->throttled_cfs_rq.next)
-		return;
-
-	hrtimer_cancel(&cfs_b->period_timer);
-	hrtimer_cancel(&cfs_b->slack_timer);
-
-	/*
-	 * It is possible that we still have some cfs_rq's pending on a CSD
-	 * list, though this race is very rare. In order for this to occur, we
-	 * must have raced with the last task leaving the group while there
-	 * exist throttled cfs_rq(s), and the period_timer must have queued the
-	 * CSD item but the remote cpu has not yet processed it. To handle this,
-	 * we can simply flush all pending CSD work inline here. We're
-	 * guaranteed at this point that no additional cfs_rq of this group can
-	 * join a CSD list.
-	 */
-#ifdef CONFIG_SMP
-	for_each_possible_cpu(i) {
-		struct rq *rq = cpu_rq(i);
-		unsigned long flags;
-
-		if (list_empty(&rq->cfsb_csd_list))
-			continue;
-
-		local_irq_save(flags);
-		__cfsb_csd_unthrottle(rq);
-		local_irq_restore(flags);
-	}
-#endif
-}
-
-/*
- * Both these CPU hotplug callbacks race against unregister_fair_sched_group()
- *
- * The race is harmless, since modifying bandwidth settings of unhooked group
- * bits doesn't do much.
- */
-
-/* cpu online callback */
-static void __maybe_unused update_runtime_enabled(struct rq *rq)
-{
-	struct task_group *tg;
-
-	lockdep_assert_rq_held(rq);
-
-	rcu_read_lock();
-	list_for_each_entry_rcu(tg, &task_groups, list) {
-		struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
-		struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
-
-		raw_spin_lock(&cfs_b->lock);
-		cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
-		raw_spin_unlock(&cfs_b->lock);
-	}
-	rcu_read_unlock();
-}
-
-/* cpu offline callback */
-static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq)
-{
-	struct task_group *tg;
-
-	lockdep_assert_rq_held(rq);
-
-	/*
-	 * The rq clock has already been updated in the
-	 * set_rq_offline(), so we should skip updating
-	 * the rq clock again in unthrottle_cfs_rq().
-	 */
-	rq_clock_start_loop_update(rq);
-
-	rcu_read_lock();
-	list_for_each_entry_rcu(tg, &task_groups, list) {
-		struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
-
-		if (!cfs_rq->runtime_enabled)
-			continue;
-
-		/*
-		 * clock_task is not advancing so we just need to make sure
-		 * there's some valid quota amount
-		 */
-		cfs_rq->runtime_remaining = 1;
-		/*
-		 * Offline rq is schedulable till CPU is completely disabled
-		 * in take_cpu_down(), so we prevent new cfs throttling here.
-		 */
-		cfs_rq->runtime_enabled = 0;
-
-		if (cfs_rq_throttled(cfs_rq))
-			unthrottle_cfs_rq(cfs_rq);
-	}
-	rcu_read_unlock();
-
-	rq_clock_stop_loop_update(rq);
-}
-
-bool cfs_task_bw_constrained(struct task_struct *p)
-{
-	struct cfs_rq *cfs_rq = task_cfs_rq(p);
-
-	if (!cfs_bandwidth_used())
-		return false;
-
-	if (cfs_rq->runtime_enabled ||
-	    tg_cfs_bandwidth(cfs_rq->tg)->hierarchical_quota != RUNTIME_INF)
-		return true;
-
-	return false;
-}
-
-#ifdef CONFIG_NO_HZ_FULL
-/* called from pick_next_task_fair() */
-static void sched_fair_update_stop_tick(struct rq *rq, struct task_struct *p)
-{
-	int cpu = cpu_of(rq);
-
-	if (!sched_feat(HZ_BW) || !cfs_bandwidth_used())
-		return;
-
-	if (!tick_nohz_full_cpu(cpu))
-		return;
-
-	if (rq->nr_running != 1)
-		return;
-
-	/*
-	 *  We know there is only one task runnable and we've just picked it. The
-	 *  normal enqueue path will have cleared TICK_DEP_BIT_SCHED if we will
-	 *  be otherwise able to stop the tick. Just need to check if we are using
-	 *  bandwidth control.
-	 */
-	if (cfs_task_bw_constrained(p))
-		tick_nohz_dep_set_cpu(cpu, TICK_DEP_BIT_SCHED);
-}
-#endif
-
-#else /* CONFIG_CFS_BANDWIDTH */
-
-static inline bool cfs_bandwidth_used(void)
-{
-	return false;
-}
-
-static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) {}
-static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) { return false; }
-static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
-static inline void sync_throttle(struct task_group *tg, int cpu) {}
-static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
-
-static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
-{
-	return 0;
-}
-
-static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
-{
-	return 0;
-}
-
-static inline int throttled_lb_pair(struct task_group *tg,
-				    int src_cpu, int dest_cpu)
-{
-	return 0;
-}
-
-#ifdef CONFIG_FAIR_GROUP_SCHED
-void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b, struct cfs_bandwidth *parent) {}
-static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
-#endif
-
-static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
-{
-	return NULL;
-}
-static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
-static inline void update_runtime_enabled(struct rq *rq) {}
-static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
-#ifdef CONFIG_CGROUP_SCHED
-bool cfs_task_bw_constrained(struct task_struct *p)
-{
-	return false;
-}
-#endif
-#endif /* CONFIG_CFS_BANDWIDTH */
-
-#if !defined(CONFIG_CFS_BANDWIDTH) || !defined(CONFIG_NO_HZ_FULL)
-static inline void sched_fair_update_stop_tick(struct rq *rq, struct task_struct *p) {}
-#endif
-
-/**************************************************
- * CFS operations on tasks:
- */
-
-#ifdef CONFIG_SCHED_HRTICK
-static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
-{
-	struct sched_entity *se = &p->se;
-
-	SCHED_WARN_ON(task_rq(p) != rq);
-
-	if (rq->cfs.h_nr_running > 1) {
-		u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
-		u64 slice = se->slice;
-		s64 delta = slice - ran;
-
-		if (delta < 0) {
-			if (task_current(rq, p))
-				resched_curr(rq);
-			return;
-		}
-		hrtick_start(rq, delta);
-	}
-}
-
-/*
- * called from enqueue/dequeue and updates the hrtick when the
- * current task is from our class and nr_running is low enough
- * to matter.
- */
-static void hrtick_update(struct rq *rq)
-{
-	struct task_struct *curr = rq->curr;
-
-	if (!hrtick_enabled_fair(rq) || curr->sched_class != &fair_sched_class)
-		return;
-
-	hrtick_start_fair(rq, curr);
-}
-#else /* !CONFIG_SCHED_HRTICK */
-static inline void
-hrtick_start_fair(struct rq *rq, struct task_struct *p)
-{
-}
-
-static inline void hrtick_update(struct rq *rq)
-{
-}
-#endif
-
-#ifdef CONFIG_SMP
-static inline bool cpu_overutilized(int cpu)
-{
-	unsigned long  rq_util_min, rq_util_max;
-
-	if (!sched_energy_enabled())
-		return false;
-
-	rq_util_min = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MIN);
-	rq_util_max = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MAX);
-
-	/* Return true only if the utilization doesn't fit CPU's capacity */
-	return !util_fits_cpu(cpu_util_cfs(cpu), rq_util_min, rq_util_max, cpu);
-}
-
-/*
- * overutilized value make sense only if EAS is enabled
- */
-static inline bool is_rd_overutilized(struct root_domain *rd)
-{
-	return !sched_energy_enabled() || READ_ONCE(rd->overutilized);
-}
-
-static inline void set_rd_overutilized(struct root_domain *rd, bool flag)
-{
-	if (!sched_energy_enabled())
-		return;
-
-	WRITE_ONCE(rd->overutilized, flag);
-	trace_sched_overutilized_tp(rd, flag);
-}
-
-static inline void check_update_overutilized_status(struct rq *rq)
-{
-	/*
-	 * overutilized field is used for load balancing decisions only
-	 * if energy aware scheduler is being used
-	 */
-
-	if (!is_rd_overutilized(rq->rd) && cpu_overutilized(rq->cpu))
-		set_rd_overutilized(rq->rd, 1);
-}
-#else
-static inline void check_update_overutilized_status(struct rq *rq) { }
-#endif
-
-/* Runqueue only has SCHED_IDLE tasks enqueued */
-static int sched_idle_rq(struct rq *rq)
-{
-	return unlikely(rq->nr_running == rq->cfs.idle_h_nr_running &&
-			rq->nr_running);
-}
-
-#ifdef CONFIG_SMP
-static int sched_idle_cpu(int cpu)
-{
-	return sched_idle_rq(cpu_rq(cpu));
-}
-#endif
-
-/*
- * The enqueue_task method is called before nr_running is
- * increased. Here we update the fair scheduling stats and
- * then put the task into the rbtree:
- */
-static void
-enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
-{
-	struct cfs_rq *cfs_rq;
-	struct sched_entity *se = &p->se;
-	int idle_h_nr_running = task_has_idle_policy(p);
-	int task_new = !(flags & ENQUEUE_WAKEUP);
-
-	/*
-	 * The code below (indirectly) updates schedutil which looks at
-	 * the cfs_rq utilization to select a frequency.
-	 * Let's add the task's estimated utilization to the cfs_rq's
-	 * estimated utilization, before we update schedutil.
-	 */
-	util_est_enqueue(&rq->cfs, p);
-
-	/*
-	 * If in_iowait is set, the code below may not trigger any cpufreq
-	 * utilization updates, so do it here explicitly with the IOWAIT flag
-	 * passed.
-	 */
-	if (p->in_iowait)
-		cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT);
-
-	for_each_sched_entity(se) {
-		if (se->on_rq)
-			break;
-		cfs_rq = cfs_rq_of(se);
-		enqueue_entity(cfs_rq, se, flags);
-
-		cfs_rq->h_nr_running++;
-		cfs_rq->idle_h_nr_running += idle_h_nr_running;
-
-		if (cfs_rq_is_idle(cfs_rq))
-			idle_h_nr_running = 1;
-
-		/* end evaluation on encountering a throttled cfs_rq */
-		if (cfs_rq_throttled(cfs_rq))
-			goto enqueue_throttle;
-
-		flags = ENQUEUE_WAKEUP;
-	}
-
-	for_each_sched_entity(se) {
-		cfs_rq = cfs_rq_of(se);
-
-		update_load_avg(cfs_rq, se, UPDATE_TG);
-		se_update_runnable(se);
-		update_cfs_group(se);
-
-		cfs_rq->h_nr_running++;
-		cfs_rq->idle_h_nr_running += idle_h_nr_running;
-
-		if (cfs_rq_is_idle(cfs_rq))
-			idle_h_nr_running = 1;
-
-		/* end evaluation on encountering a throttled cfs_rq */
-		if (cfs_rq_throttled(cfs_rq))
-			goto enqueue_throttle;
-	}
-
-	/* At this point se is NULL and we are at root level*/
-	add_nr_running(rq, 1);
-
-	/*
-	 * Since new tasks are assigned an initial util_avg equal to
-	 * half of the spare capacity of their CPU, tiny tasks have the
-	 * ability to cross the overutilized threshold, which will
-	 * result in the load balancer ruining all the task placement
-	 * done by EAS. As a way to mitigate that effect, do not account
-	 * for the first enqueue operation of new tasks during the
-	 * overutilized flag detection.
-	 *
-	 * A better way of solving this problem would be to wait for
-	 * the PELT signals of tasks to converge before taking them
-	 * into account, but that is not straightforward to implement,
-	 * and the following generally works well enough in practice.
-	 */
-	if (!task_new)
-		check_update_overutilized_status(rq);
-
-enqueue_throttle:
-	assert_list_leaf_cfs_rq(rq);
-
-	hrtick_update(rq);
-}
-
-static void set_next_buddy(struct sched_entity *se);
-
-/*
- * The dequeue_task method is called before nr_running is
- * decreased. We remove the task from the rbtree and
- * update the fair scheduling stats:
- */
-static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
-{
-	struct cfs_rq *cfs_rq;
-	struct sched_entity *se = &p->se;
-	int task_sleep = flags & DEQUEUE_SLEEP;
-	int idle_h_nr_running = task_has_idle_policy(p);
-	bool was_sched_idle = sched_idle_rq(rq);
-
-	util_est_dequeue(&rq->cfs, p);
-
-	for_each_sched_entity(se) {
-		cfs_rq = cfs_rq_of(se);
-		dequeue_entity(cfs_rq, se, flags);
-
-		cfs_rq->h_nr_running--;
-		cfs_rq->idle_h_nr_running -= idle_h_nr_running;
-
-		if (cfs_rq_is_idle(cfs_rq))
-			idle_h_nr_running = 1;
-
-		/* end evaluation on encountering a throttled cfs_rq */
-		if (cfs_rq_throttled(cfs_rq))
-			goto dequeue_throttle;
-
-		/* Don't dequeue parent if it has other entities besides us */
-		if (cfs_rq->load.weight) {
-			/* Avoid re-evaluating load for this entity: */
-			se = parent_entity(se);
-			/*
-			 * Bias pick_next to pick a task from this cfs_rq, as
-			 * p is sleeping when it is within its sched_slice.
-			 */
-			if (task_sleep && se && !throttled_hierarchy(cfs_rq))
-				set_next_buddy(se);
-			break;
-		}
-		flags |= DEQUEUE_SLEEP;
-	}
-
-	for_each_sched_entity(se) {
-		cfs_rq = cfs_rq_of(se);
-
-		update_load_avg(cfs_rq, se, UPDATE_TG);
-		se_update_runnable(se);
-		update_cfs_group(se);
-
-		cfs_rq->h_nr_running--;
-		cfs_rq->idle_h_nr_running -= idle_h_nr_running;
-
-		if (cfs_rq_is_idle(cfs_rq))
-			idle_h_nr_running = 1;
-
-		/* end evaluation on encountering a throttled cfs_rq */
-		if (cfs_rq_throttled(cfs_rq))
-			goto dequeue_throttle;
-
-	}
-
-	/* At this point se is NULL and we are at root level*/
-	sub_nr_running(rq, 1);
-
-	/* balance early to pull high priority tasks */
-	if (unlikely(!was_sched_idle && sched_idle_rq(rq)))
-		rq->next_balance = jiffies;
-
-dequeue_throttle:
-	util_est_update(&rq->cfs, p, task_sleep);
-	hrtick_update(rq);
-}
-
-#ifdef CONFIG_SMP
-
-/* Working cpumask for: sched_balance_rq(), sched_balance_newidle(). */
-static DEFINE_PER_CPU(cpumask_var_t, load_balance_mask);
-static DEFINE_PER_CPU(cpumask_var_t, select_rq_mask);
-static DEFINE_PER_CPU(cpumask_var_t, should_we_balance_tmpmask);
-
-#ifdef CONFIG_NO_HZ_COMMON
-
-static struct {
-	cpumask_var_t idle_cpus_mask;
-	atomic_t nr_cpus;
-	int has_blocked;		/* Idle CPUS has blocked load */
-	int needs_update;		/* Newly idle CPUs need their next_balance collated */
-	unsigned long next_balance;     /* in jiffy units */
-	unsigned long next_blocked;	/* Next update of blocked load in jiffies */
-} nohz ____cacheline_aligned;
-
-#endif /* CONFIG_NO_HZ_COMMON */
-
-static unsigned long cpu_load(struct rq *rq)
-{
-	return cfs_rq_load_avg(&rq->cfs);
-}
-
-/*
- * cpu_load_without - compute CPU load without any contributions from *p
- * @cpu: the CPU which load is requested
- * @p: the task which load should be discounted
- *
- * The load of a CPU is defined by the load of tasks currently enqueued on that
- * CPU as well as tasks which are currently sleeping after an execution on that
- * CPU.
- *
- * This method returns the load of the specified CPU by discounting the load of
- * the specified task, whenever the task is currently contributing to the CPU
- * load.
- */
-static unsigned long cpu_load_without(struct rq *rq, struct task_struct *p)
-{
-	struct cfs_rq *cfs_rq;
-	unsigned int load;
-
-	/* Task has no contribution or is new */
-	if (cpu_of(rq) != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
-		return cpu_load(rq);
-
-	cfs_rq = &rq->cfs;
-	load = READ_ONCE(cfs_rq->avg.load_avg);
-
-	/* Discount task's util from CPU's util */
-	lsub_positive(&load, task_h_load(p));
-
-	return load;
-}
-
-static unsigned long cpu_runnable(struct rq *rq)
-{
-	return cfs_rq_runnable_avg(&rq->cfs);
-}
-
-static unsigned long cpu_runnable_without(struct rq *rq, struct task_struct *p)
-{
-	struct cfs_rq *cfs_rq;
-	unsigned int runnable;
-
-	/* Task has no contribution or is new */
-	if (cpu_of(rq) != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
-		return cpu_runnable(rq);
-
-	cfs_rq = &rq->cfs;
-	runnable = READ_ONCE(cfs_rq->avg.runnable_avg);
-
-	/* Discount task's runnable from CPU's runnable */
-	lsub_positive(&runnable, p->se.avg.runnable_avg);
-
-	return runnable;
-}
-
-static unsigned long capacity_of(int cpu)
-{
-	return cpu_rq(cpu)->cpu_capacity;
-}
-
-static void record_wakee(struct task_struct *p)
-{
-	/*
-	 * Only decay a single time; tasks that have less then 1 wakeup per
-	 * jiffy will not have built up many flips.
-	 */
-	if (time_after(jiffies, current->wakee_flip_decay_ts + HZ)) {
-		current->wakee_flips >>= 1;
-		current->wakee_flip_decay_ts = jiffies;
-	}
-
-	if (current->last_wakee != p) {
-		current->last_wakee = p;
-		current->wakee_flips++;
-	}
-}
-
-/*
- * Detect M:N waker/wakee relationships via a switching-frequency heuristic.
- *
- * A waker of many should wake a different task than the one last awakened
- * at a frequency roughly N times higher than one of its wakees.
- *
- * In order to determine whether we should let the load spread vs consolidating
- * to shared cache, we look for a minimum 'flip' frequency of llc_size in one
- * partner, and a factor of lls_size higher frequency in the other.
- *
- * With both conditions met, we can be relatively sure that the relationship is
- * non-monogamous, with partner count exceeding socket size.
- *
- * Waker/wakee being client/server, worker/dispatcher, interrupt source or
- * whatever is irrelevant, spread criteria is apparent partner count exceeds
- * socket size.
- */
-static int wake_wide(struct task_struct *p)
-{
-	unsigned int master = current->wakee_flips;
-	unsigned int slave = p->wakee_flips;
-	int factor = __this_cpu_read(sd_llc_size);
-
-	if (master < slave)
-		swap(master, slave);
-	if (slave < factor || master < slave * factor)
-		return 0;
-	return 1;
-}
-
-/*
- * The purpose of wake_affine() is to quickly determine on which CPU we can run
- * soonest. For the purpose of speed we only consider the waking and previous
- * CPU.
- *
- * wake_affine_idle() - only considers 'now', it check if the waking CPU is
- *			cache-affine and is (or	will be) idle.
- *
- * wake_affine_weight() - considers the weight to reflect the average
- *			  scheduling latency of the CPUs. This seems to work
- *			  for the overloaded case.
- */
-static int
-wake_affine_idle(int this_cpu, int prev_cpu, int sync)
-{
-	/*
-	 * If this_cpu is idle, it implies the wakeup is from interrupt
-	 * context. Only allow the move if cache is shared. Otherwise an
-	 * interrupt intensive workload could force all tasks onto one
-	 * node depending on the IO topology or IRQ affinity settings.
-	 *
-	 * If the prev_cpu is idle and cache affine then avoid a migration.
-	 * There is no guarantee that the cache hot data from an interrupt
-	 * is more important than cache hot data on the prev_cpu and from
-	 * a cpufreq perspective, it's better to have higher utilisation
-	 * on one CPU.
-	 */
-	if (available_idle_cpu(this_cpu) && cpus_share_cache(this_cpu, prev_cpu))
-		return available_idle_cpu(prev_cpu) ? prev_cpu : this_cpu;
-
-	if (sync && cpu_rq(this_cpu)->nr_running == 1)
-		return this_cpu;
-
-	if (available_idle_cpu(prev_cpu))
-		return prev_cpu;
-
-	return nr_cpumask_bits;
-}
-
-static int
-wake_affine_weight(struct sched_domain *sd, struct task_struct *p,
-		   int this_cpu, int prev_cpu, int sync)
-{
-	s64 this_eff_load, prev_eff_load;
-	unsigned long task_load;
-
-	this_eff_load = cpu_load(cpu_rq(this_cpu));
-
-	if (sync) {
-		unsigned long current_load = task_h_load(current);
-
-		if (current_load > this_eff_load)
-			return this_cpu;
-
-		this_eff_load -= current_load;
-	}
-
-	task_load = task_h_load(p);
-
-	this_eff_load += task_load;
-	if (sched_feat(WA_BIAS))
-		this_eff_load *= 100;
-	this_eff_load *= capacity_of(prev_cpu);
-
-	prev_eff_load = cpu_load(cpu_rq(prev_cpu));
-	prev_eff_load -= task_load;
-	if (sched_feat(WA_BIAS))
-		prev_eff_load *= 100 + (sd->imbalance_pct - 100) / 2;
-	prev_eff_load *= capacity_of(this_cpu);
-
-	/*
-	 * If sync, adjust the weight of prev_eff_load such that if
-	 * prev_eff == this_eff that select_idle_sibling() will consider
-	 * stacking the wakee on top of the waker if no other CPU is
-	 * idle.
-	 */
-	if (sync)
-		prev_eff_load += 1;
-
-	return this_eff_load < prev_eff_load ? this_cpu : nr_cpumask_bits;
-}
-
-static int wake_affine(struct sched_domain *sd, struct task_struct *p,
-		       int this_cpu, int prev_cpu, int sync)
-{
-	int target = nr_cpumask_bits;
-
-	if (sched_feat(WA_IDLE))
-		target = wake_affine_idle(this_cpu, prev_cpu, sync);
-
-	if (sched_feat(WA_WEIGHT) && target == nr_cpumask_bits)
-		target = wake_affine_weight(sd, p, this_cpu, prev_cpu, sync);
-
-	schedstat_inc(p->stats.nr_wakeups_affine_attempts);
-	if (target != this_cpu)
-		return prev_cpu;
-
-	schedstat_inc(sd->ttwu_move_affine);
-	schedstat_inc(p->stats.nr_wakeups_affine);
-	return target;
-}
-
-static struct sched_group *
-sched_balance_find_dst_group(struct sched_domain *sd, struct task_struct *p, int this_cpu);
-
-/*
- * sched_balance_find_dst_group_cpu - find the idlest CPU among the CPUs in the group.
- */
-static int
-sched_balance_find_dst_group_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
-{
-	unsigned long load, min_load = ULONG_MAX;
-	unsigned int min_exit_latency = UINT_MAX;
-	u64 latest_idle_timestamp = 0;
-	int least_loaded_cpu = this_cpu;
-	int shallowest_idle_cpu = -1;
-	int i;
-
-	/* Check if we have any choice: */
-	if (group->group_weight == 1)
-		return cpumask_first(sched_group_span(group));
-
-	/* Traverse only the allowed CPUs */
-	for_each_cpu_and(i, sched_group_span(group), p->cpus_ptr) {
-		struct rq *rq = cpu_rq(i);
-
-		if (!sched_core_cookie_match(rq, p))
-			continue;
-
-		if (sched_idle_cpu(i))
-			return i;
-
-		if (available_idle_cpu(i)) {
-			struct cpuidle_state *idle = idle_get_state(rq);
-			if (idle && idle->exit_latency < min_exit_latency) {
-				/*
-				 * We give priority to a CPU whose idle state
-				 * has the smallest exit latency irrespective
-				 * of any idle timestamp.
-				 */
-				min_exit_latency = idle->exit_latency;
-				latest_idle_timestamp = rq->idle_stamp;
-				shallowest_idle_cpu = i;
-			} else if ((!idle || idle->exit_latency == min_exit_latency) &&
-				   rq->idle_stamp > latest_idle_timestamp) {
-				/*
-				 * If equal or no active idle state, then
-				 * the most recently idled CPU might have
-				 * a warmer cache.
-				 */
-				latest_idle_timestamp = rq->idle_stamp;
-				shallowest_idle_cpu = i;
-			}
-		} else if (shallowest_idle_cpu == -1) {
-			load = cpu_load(cpu_rq(i));
-			if (load < min_load) {
-				min_load = load;
-				least_loaded_cpu = i;
-			}
-		}
-	}
-
-	return shallowest_idle_cpu != -1 ? shallowest_idle_cpu : least_loaded_cpu;
-}
-
-static inline int sched_balance_find_dst_cpu(struct sched_domain *sd, struct task_struct *p,
-				  int cpu, int prev_cpu, int sd_flag)
-{
-	int new_cpu = cpu;
-
-	if (!cpumask_intersects(sched_domain_span(sd), p->cpus_ptr))
-		return prev_cpu;
-
-	/*
-	 * We need task's util for cpu_util_without, sync it up to
-	 * prev_cpu's last_update_time.
-	 */
-	if (!(sd_flag & SD_BALANCE_FORK))
-		sync_entity_load_avg(&p->se);
-
-	while (sd) {
-		struct sched_group *group;
-		struct sched_domain *tmp;
-		int weight;
-
-		if (!(sd->flags & sd_flag)) {
-			sd = sd->child;
-			continue;
-		}
-
-		group = sched_balance_find_dst_group(sd, p, cpu);
-		if (!group) {
-			sd = sd->child;
-			continue;
-		}
-
-		new_cpu = sched_balance_find_dst_group_cpu(group, p, cpu);
-		if (new_cpu == cpu) {
-			/* Now try balancing at a lower domain level of 'cpu': */
-			sd = sd->child;
-			continue;
-		}
-
-		/* Now try balancing at a lower domain level of 'new_cpu': */
-		cpu = new_cpu;
-		weight = sd->span_weight;
-		sd = NULL;
-		for_each_domain(cpu, tmp) {
-			if (weight <= tmp->span_weight)
-				break;
-			if (tmp->flags & sd_flag)
-				sd = tmp;
-		}
-	}
-
-	return new_cpu;
-}
-
-static inline int __select_idle_cpu(int cpu, struct task_struct *p)
-{
-	if ((available_idle_cpu(cpu) || sched_idle_cpu(cpu)) &&
-	    sched_cpu_cookie_match(cpu_rq(cpu), p))
-		return cpu;
-
-	return -1;
-}
-
-#ifdef CONFIG_SCHED_SMT
-DEFINE_STATIC_KEY_FALSE(sched_smt_present);
-EXPORT_SYMBOL_GPL(sched_smt_present);
-
-static inline void set_idle_cores(int cpu, int val)
-{
-	struct sched_domain_shared *sds;
-
-	sds = rcu_dereference(per_cpu(sd_llc_shared, cpu));
-	if (sds)
-		WRITE_ONCE(sds->has_idle_cores, val);
-}
-
-static inline bool test_idle_cores(int cpu)
-{
-	struct sched_domain_shared *sds;
-
-	sds = rcu_dereference(per_cpu(sd_llc_shared, cpu));
-	if (sds)
-		return READ_ONCE(sds->has_idle_cores);
-
-	return false;
-}
-
-/*
- * Scans the local SMT mask to see if the entire core is idle, and records this
- * information in sd_llc_shared->has_idle_cores.
- *
- * Since SMT siblings share all cache levels, inspecting this limited remote
- * state should be fairly cheap.
- */
-void __update_idle_core(struct rq *rq)
-{
-	int core = cpu_of(rq);
-	int cpu;
-
-	rcu_read_lock();
-	if (test_idle_cores(core))
-		goto unlock;
-
-	for_each_cpu(cpu, cpu_smt_mask(core)) {
-		if (cpu == core)
-			continue;
-
-		if (!available_idle_cpu(cpu))
-			goto unlock;
-	}
-
-	set_idle_cores(core, 1);
-unlock:
-	rcu_read_unlock();
-}
-
-/*
- * Scan the entire LLC domain for idle cores; this dynamically switches off if
- * there are no idle cores left in the system; tracked through
- * sd_llc->shared->has_idle_cores and enabled through update_idle_core() above.
- */
-static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu)
-{
-	bool idle = true;
-	int cpu;
-
-	for_each_cpu(cpu, cpu_smt_mask(core)) {
-		if (!available_idle_cpu(cpu)) {
-			idle = false;
-			if (*idle_cpu == -1) {
-				if (sched_idle_cpu(cpu) && cpumask_test_cpu(cpu, cpus)) {
-					*idle_cpu = cpu;
-					break;
-				}
-				continue;
-			}
-			break;
-		}
-		if (*idle_cpu == -1 && cpumask_test_cpu(cpu, cpus))
-			*idle_cpu = cpu;
-	}
-
-	if (idle)
-		return core;
-
-	cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
-	return -1;
-}
-
-/*
- * Scan the local SMT mask for idle CPUs.
- */
-static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
-{
-	int cpu;
-
-	for_each_cpu_and(cpu, cpu_smt_mask(target), p->cpus_ptr) {
-		if (cpu == target)
-			continue;
-		/*
-		 * Check if the CPU is in the LLC scheduling domain of @target.
-		 * Due to isolcpus, there is no guarantee that all the siblings are in the domain.
-		 */
-		if (!cpumask_test_cpu(cpu, sched_domain_span(sd)))
-			continue;
-		if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
-			return cpu;
-	}
-
-	return -1;
-}
-
-#else /* CONFIG_SCHED_SMT */
-
-static inline void set_idle_cores(int cpu, int val)
-{
-}
-
-static inline bool test_idle_cores(int cpu)
-{
-	return false;
-}
-
-static inline int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu)
-{
-	return __select_idle_cpu(core, p);
-}
-
-static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
-{
-	return -1;
-}
-
-#endif /* CONFIG_SCHED_SMT */
-
-/*
- * Scan the LLC domain for idle CPUs; this is dynamically regulated by
- * comparing the average scan cost (tracked in sd->avg_scan_cost) against the
- * average idle time for this rq (as found in rq->avg_idle).
- */
-static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool has_idle_core, int target)
-{
-	struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
-	int i, cpu, idle_cpu = -1, nr = INT_MAX;
-	struct sched_domain_shared *sd_share;
-
-	cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
-
-	if (sched_feat(SIS_UTIL)) {
-		sd_share = rcu_dereference(per_cpu(sd_llc_shared, target));
-		if (sd_share) {
-			/* because !--nr is the condition to stop scan */
-			nr = READ_ONCE(sd_share->nr_idle_scan) + 1;
-			/* overloaded LLC is unlikely to have idle cpu/core */
-			if (nr == 1)
-				return -1;
-		}
-	}
-
-	if (static_branch_unlikely(&sched_cluster_active)) {
-		struct sched_group *sg = sd->groups;
-
-		if (sg->flags & SD_CLUSTER) {
-			for_each_cpu_wrap(cpu, sched_group_span(sg), target + 1) {
-				if (!cpumask_test_cpu(cpu, cpus))
-					continue;
-
-				if (has_idle_core) {
-					i = select_idle_core(p, cpu, cpus, &idle_cpu);
-					if ((unsigned int)i < nr_cpumask_bits)
-						return i;
-				} else {
-					if (--nr <= 0)
-						return -1;
-					idle_cpu = __select_idle_cpu(cpu, p);
-					if ((unsigned int)idle_cpu < nr_cpumask_bits)
-						return idle_cpu;
-				}
-			}
-			cpumask_andnot(cpus, cpus, sched_group_span(sg));
-		}
-	}
-
-	for_each_cpu_wrap(cpu, cpus, target + 1) {
-		if (has_idle_core) {
-			i = select_idle_core(p, cpu, cpus, &idle_cpu);
-			if ((unsigned int)i < nr_cpumask_bits)
-				return i;
-
-		} else {
-			if (--nr <= 0)
-				return -1;
-			idle_cpu = __select_idle_cpu(cpu, p);
-			if ((unsigned int)idle_cpu < nr_cpumask_bits)
-				break;
-		}
-	}
-
-	if (has_idle_core)
-		set_idle_cores(target, false);
-
-	return idle_cpu;
-}
-
-/*
- * Scan the asym_capacity domain for idle CPUs; pick the first idle one on which
- * the task fits. If no CPU is big enough, but there are idle ones, try to
- * maximize capacity.
- */
-static int
-select_idle_capacity(struct task_struct *p, struct sched_domain *sd, int target)
-{
-	unsigned long task_util, util_min, util_max, best_cap = 0;
-	int fits, best_fits = 0;
-	int cpu, best_cpu = -1;
-	struct cpumask *cpus;
-
-	cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
-	cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
-
-	task_util = task_util_est(p);
-	util_min = uclamp_eff_value(p, UCLAMP_MIN);
-	util_max = uclamp_eff_value(p, UCLAMP_MAX);
-
-	for_each_cpu_wrap(cpu, cpus, target) {
-		unsigned long cpu_cap = capacity_of(cpu);
-
-		if (!available_idle_cpu(cpu) && !sched_idle_cpu(cpu))
-			continue;
-
-		fits = util_fits_cpu(task_util, util_min, util_max, cpu);
-
-		/* This CPU fits with all requirements */
-		if (fits > 0)
-			return cpu;
-		/*
-		 * Only the min performance hint (i.e. uclamp_min) doesn't fit.
-		 * Look for the CPU with best capacity.
-		 */
-		else if (fits < 0)
-			cpu_cap = arch_scale_cpu_capacity(cpu) - thermal_load_avg(cpu_rq(cpu));
-
-		/*
-		 * First, select CPU which fits better (-1 being better than 0).
-		 * Then, select the one with best capacity at same level.
-		 */
-		if ((fits < best_fits) ||
-		    ((fits == best_fits) && (cpu_cap > best_cap))) {
-			best_cap = cpu_cap;
-			best_cpu = cpu;
-			best_fits = fits;
-		}
-	}
-
-	return best_cpu;
-}
-
-static inline bool asym_fits_cpu(unsigned long util,
-				 unsigned long util_min,
-				 unsigned long util_max,
-				 int cpu)
-{
-	if (sched_asym_cpucap_active())
-		/*
-		 * Return true only if the cpu fully fits the task requirements
-		 * which include the utilization and the performance hints.
-		 */
-		return (util_fits_cpu(util, util_min, util_max, cpu) > 0);
-
-	return true;
-}
-
-/*
- * Try and locate an idle core/thread in the LLC cache domain.
- */
-static int select_idle_sibling(struct task_struct *p, int prev, int target)
-{
-	bool has_idle_core = false;
-	struct sched_domain *sd;
-	unsigned long task_util, util_min, util_max;
-	int i, recent_used_cpu, prev_aff = -1;
-
-	/*
-	 * On asymmetric system, update task utilization because we will check
-	 * that the task fits with CPU's capacity.
-	 */
-	if (sched_asym_cpucap_active()) {
-		sync_entity_load_avg(&p->se);
-		task_util = task_util_est(p);
-		util_min = uclamp_eff_value(p, UCLAMP_MIN);
-		util_max = uclamp_eff_value(p, UCLAMP_MAX);
-	}
-
-	/*
-	 * per-cpu select_rq_mask usage
-	 */
-	lockdep_assert_irqs_disabled();
-
-	if ((available_idle_cpu(target) || sched_idle_cpu(target)) &&
-	    asym_fits_cpu(task_util, util_min, util_max, target))
-		return target;
-
-	/*
-	 * If the previous CPU is cache affine and idle, don't be stupid:
-	 */
-	if (prev != target && cpus_share_cache(prev, target) &&
-	    (available_idle_cpu(prev) || sched_idle_cpu(prev)) &&
-	    asym_fits_cpu(task_util, util_min, util_max, prev)) {
-
-		if (!static_branch_unlikely(&sched_cluster_active) ||
-		    cpus_share_resources(prev, target))
-			return prev;
-
-		prev_aff = prev;
-	}
-
-	/*
-	 * Allow a per-cpu kthread to stack with the wakee if the
-	 * kworker thread and the tasks previous CPUs are the same.
-	 * The assumption is that the wakee queued work for the
-	 * per-cpu kthread that is now complete and the wakeup is
-	 * essentially a sync wakeup. An obvious example of this
-	 * pattern is IO completions.
-	 */
-	if (is_per_cpu_kthread(current) &&
-	    in_task() &&
-	    prev == smp_processor_id() &&
-	    this_rq()->nr_running <= 1 &&
-	    asym_fits_cpu(task_util, util_min, util_max, prev)) {
-		return prev;
-	}
-
-	/* Check a recently used CPU as a potential idle candidate: */
-	recent_used_cpu = p->recent_used_cpu;
-	p->recent_used_cpu = prev;
-	if (recent_used_cpu != prev &&
-	    recent_used_cpu != target &&
-	    cpus_share_cache(recent_used_cpu, target) &&
-	    (available_idle_cpu(recent_used_cpu) || sched_idle_cpu(recent_used_cpu)) &&
-	    cpumask_test_cpu(recent_used_cpu, p->cpus_ptr) &&
-	    asym_fits_cpu(task_util, util_min, util_max, recent_used_cpu)) {
-
-		if (!static_branch_unlikely(&sched_cluster_active) ||
-		    cpus_share_resources(recent_used_cpu, target))
-			return recent_used_cpu;
-
-	} else {
-		recent_used_cpu = -1;
-	}
-
-	/*
-	 * For asymmetric CPU capacity systems, our domain of interest is
-	 * sd_asym_cpucapacity rather than sd_llc.
-	 */
-	if (sched_asym_cpucap_active()) {
-		sd = rcu_dereference(per_cpu(sd_asym_cpucapacity, target));
-		/*
-		 * On an asymmetric CPU capacity system where an exclusive
-		 * cpuset defines a symmetric island (i.e. one unique
-		 * capacity_orig value through the cpuset), the key will be set
-		 * but the CPUs within that cpuset will not have a domain with
-		 * SD_ASYM_CPUCAPACITY. These should follow the usual symmetric
-		 * capacity path.
-		 */
-		if (sd) {
-			i = select_idle_capacity(p, sd, target);
-			return ((unsigned)i < nr_cpumask_bits) ? i : target;
-		}
-	}
-
-	sd = rcu_dereference(per_cpu(sd_llc, target));
-	if (!sd)
-		return target;
-
-	if (sched_smt_active()) {
-		has_idle_core = test_idle_cores(target);
-
-		if (!has_idle_core && cpus_share_cache(prev, target)) {
-			i = select_idle_smt(p, sd, prev);
-			if ((unsigned int)i < nr_cpumask_bits)
-				return i;
-		}
-	}
-
-	i = select_idle_cpu(p, sd, has_idle_core, target);
-	if ((unsigned)i < nr_cpumask_bits)
-		return i;
-
-	/*
-	 * For cluster machines which have lower sharing cache like L2 or
-	 * LLC Tag, we tend to find an idle CPU in the target's cluster
-	 * first. But prev_cpu or recent_used_cpu may also be a good candidate,
-	 * use them if possible when no idle CPU found in select_idle_cpu().
-	 */
-	if ((unsigned int)prev_aff < nr_cpumask_bits)
-		return prev_aff;
-	if ((unsigned int)recent_used_cpu < nr_cpumask_bits)
-		return recent_used_cpu;
-
-	return target;
-}
-
-/**
- * cpu_util() - Estimates the amount of CPU capacity used by CFS tasks.
- * @cpu: the CPU to get the utilization for
- * @p: task for which the CPU utilization should be predicted or NULL
- * @dst_cpu: CPU @p migrates to, -1 if @p moves from @cpu or @p == NULL
- * @boost: 1 to enable boosting, otherwise 0
- *
- * The unit of the return value must be the same as the one of CPU capacity
- * so that CPU utilization can be compared with CPU capacity.
- *
- * CPU utilization is the sum of running time of runnable tasks plus the
- * recent utilization of currently non-runnable tasks on that CPU.
- * It represents the amount of CPU capacity currently used by CFS tasks in
- * the range [0..max CPU capacity] with max CPU capacity being the CPU
- * capacity at f_max.
- *
- * The estimated CPU utilization is defined as the maximum between CPU
- * utilization and sum of the estimated utilization of the currently
- * runnable tasks on that CPU. It preserves a utilization "snapshot" of
- * previously-executed tasks, which helps better deduce how busy a CPU will
- * be when a long-sleeping task wakes up. The contribution to CPU utilization
- * of such a task would be significantly decayed at this point of time.
- *
- * Boosted CPU utilization is defined as max(CPU runnable, CPU utilization).
- * CPU contention for CFS tasks can be detected by CPU runnable > CPU
- * utilization. Boosting is implemented in cpu_util() so that internal
- * users (e.g. EAS) can use it next to external users (e.g. schedutil),
- * latter via cpu_util_cfs_boost().
- *
- * CPU utilization can be higher than the current CPU capacity
- * (f_curr/f_max * max CPU capacity) or even the max CPU capacity because
- * of rounding errors as well as task migrations or wakeups of new tasks.
- * CPU utilization has to be capped to fit into the [0..max CPU capacity]
- * range. Otherwise a group of CPUs (CPU0 util = 121% + CPU1 util = 80%)
- * could be seen as over-utilized even though CPU1 has 20% of spare CPU
- * capacity. CPU utilization is allowed to overshoot current CPU capacity
- * though since this is useful for predicting the CPU capacity required
- * after task migrations (scheduler-driven DVFS).
- *
- * Return: (Boosted) (estimated) utilization for the specified CPU.
- */
-static unsigned long
-cpu_util(int cpu, struct task_struct *p, int dst_cpu, int boost)
-{
-	struct cfs_rq *cfs_rq = &cpu_rq(cpu)->cfs;
-	unsigned long util = READ_ONCE(cfs_rq->avg.util_avg);
-	unsigned long runnable;
-
-	if (boost) {
-		runnable = READ_ONCE(cfs_rq->avg.runnable_avg);
-		util = max(util, runnable);
-	}
-
-	/*
-	 * If @dst_cpu is -1 or @p migrates from @cpu to @dst_cpu remove its
-	 * contribution. If @p migrates from another CPU to @cpu add its
-	 * contribution. In all the other cases @cpu is not impacted by the
-	 * migration so its util_avg is already correct.
-	 */
-	if (p && task_cpu(p) == cpu && dst_cpu != cpu)
-		lsub_positive(&util, task_util(p));
-	else if (p && task_cpu(p) != cpu && dst_cpu == cpu)
-		util += task_util(p);
-
-	if (sched_feat(UTIL_EST)) {
-		unsigned long util_est;
-
-		util_est = READ_ONCE(cfs_rq->avg.util_est);
-
-		/*
-		 * During wake-up @p isn't enqueued yet and doesn't contribute
-		 * to any cpu_rq(cpu)->cfs.avg.util_est.
-		 * If @dst_cpu == @cpu add it to "simulate" cpu_util after @p
-		 * has been enqueued.
-		 *
-		 * During exec (@dst_cpu = -1) @p is enqueued and does
-		 * contribute to cpu_rq(cpu)->cfs.util_est.
-		 * Remove it to "simulate" cpu_util without @p's contribution.
-		 *
-		 * Despite the task_on_rq_queued(@p) check there is still a
-		 * small window for a possible race when an exec
-		 * select_task_rq_fair() races with LB's detach_task().
-		 *
-		 *   detach_task()
-		 *     deactivate_task()
-		 *       p->on_rq = TASK_ON_RQ_MIGRATING;
-		 *       -------------------------------- A
-		 *       dequeue_task()                    \
-		 *         dequeue_task_fair()              + Race Time
-		 *           util_est_dequeue()            /
-		 *       -------------------------------- B
-		 *
-		 * The additional check "current == p" is required to further
-		 * reduce the race window.
-		 */
-		if (dst_cpu == cpu)
-			util_est += _task_util_est(p);
-		else if (p && unlikely(task_on_rq_queued(p) || current == p))
-			lsub_positive(&util_est, _task_util_est(p));
-
-		util = max(util, util_est);
-	}
-
-	return min(util, arch_scale_cpu_capacity(cpu));
-}
-
-unsigned long cpu_util_cfs(int cpu)
-{
-	return cpu_util(cpu, NULL, -1, 0);
-}
-
-unsigned long cpu_util_cfs_boost(int cpu)
-{
-	return cpu_util(cpu, NULL, -1, 1);
-}
-
-/*
- * cpu_util_without: compute cpu utilization without any contributions from *p
- * @cpu: the CPU which utilization is requested
- * @p: the task which utilization should be discounted
- *
- * The utilization of a CPU is defined by the utilization of tasks currently
- * enqueued on that CPU as well as tasks which are currently sleeping after an
- * execution on that CPU.
- *
- * This method returns the utilization of the specified CPU by discounting the
- * utilization of the specified task, whenever the task is currently
- * contributing to the CPU utilization.
- */
-static unsigned long cpu_util_without(int cpu, struct task_struct *p)
-{
-	/* Task has no contribution or is new */
-	if (cpu != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
-		p = NULL;
-
-	return cpu_util(cpu, p, -1, 0);
-}
-
-/*
- * energy_env - Utilization landscape for energy estimation.
- * @task_busy_time: Utilization contribution by the task for which we test the
- *                  placement. Given by eenv_task_busy_time().
- * @pd_busy_time:   Utilization of the whole perf domain without the task
- *                  contribution. Given by eenv_pd_busy_time().
- * @cpu_cap:        Maximum CPU capacity for the perf domain.
- * @pd_cap:         Entire perf domain capacity. (pd->nr_cpus * cpu_cap).
- */
-struct energy_env {
-	unsigned long task_busy_time;
-	unsigned long pd_busy_time;
-	unsigned long cpu_cap;
-	unsigned long pd_cap;
-};
-
-/*
- * Compute the task busy time for compute_energy(). This time cannot be
- * injected directly into effective_cpu_util() because of the IRQ scaling.
- * The latter only makes sense with the most recent CPUs where the task has
- * run.
- */
-static inline void eenv_task_busy_time(struct energy_env *eenv,
-				       struct task_struct *p, int prev_cpu)
-{
-	unsigned long busy_time, max_cap = arch_scale_cpu_capacity(prev_cpu);
-	unsigned long irq = cpu_util_irq(cpu_rq(prev_cpu));
-
-	if (unlikely(irq >= max_cap))
-		busy_time = max_cap;
-	else
-		busy_time = scale_irq_capacity(task_util_est(p), irq, max_cap);
-
-	eenv->task_busy_time = busy_time;
-}
-
-/*
- * Compute the perf_domain (PD) busy time for compute_energy(). Based on the
- * utilization for each @pd_cpus, it however doesn't take into account
- * clamping since the ratio (utilization / cpu_capacity) is already enough to
- * scale the EM reported power consumption at the (eventually clamped)
- * cpu_capacity.
- *
- * The contribution of the task @p for which we want to estimate the
- * energy cost is removed (by cpu_util()) and must be calculated
- * separately (see eenv_task_busy_time). This ensures:
- *
- *   - A stable PD utilization, no matter which CPU of that PD we want to place
- *     the task on.
- *
- *   - A fair comparison between CPUs as the task contribution (task_util())
- *     will always be the same no matter which CPU utilization we rely on
- *     (util_avg or util_est).
- *
- * Set @eenv busy time for the PD that spans @pd_cpus. This busy time can't
- * exceed @eenv->pd_cap.
- */
-static inline void eenv_pd_busy_time(struct energy_env *eenv,
-				     struct cpumask *pd_cpus,
-				     struct task_struct *p)
-{
-	unsigned long busy_time = 0;
-	int cpu;
-
-	for_each_cpu(cpu, pd_cpus) {
-		unsigned long util = cpu_util(cpu, p, -1, 0);
-
-		busy_time += effective_cpu_util(cpu, util, NULL, NULL);
-	}
-
-	eenv->pd_busy_time = min(eenv->pd_cap, busy_time);
-}
-
-/*
- * Compute the maximum utilization for compute_energy() when the task @p
- * is placed on the cpu @dst_cpu.
- *
- * Returns the maximum utilization among @eenv->cpus. This utilization can't
- * exceed @eenv->cpu_cap.
- */
-static inline unsigned long
-eenv_pd_max_util(struct energy_env *eenv, struct cpumask *pd_cpus,
-		 struct task_struct *p, int dst_cpu)
-{
-	unsigned long max_util = 0;
-	int cpu;
-
-	for_each_cpu(cpu, pd_cpus) {
-		struct task_struct *tsk = (cpu == dst_cpu) ? p : NULL;
-		unsigned long util = cpu_util(cpu, p, dst_cpu, 1);
-		unsigned long eff_util, min, max;
-
-		/*
-		 * Performance domain frequency: utilization clamping
-		 * must be considered since it affects the selection
-		 * of the performance domain frequency.
-		 * NOTE: in case RT tasks are running, by default the
-		 * FREQUENCY_UTIL's utilization can be max OPP.
-		 */
-		eff_util = effective_cpu_util(cpu, util, &min, &max);
-
-		/* Task's uclamp can modify min and max value */
-		if (tsk && uclamp_is_used()) {
-			min = max(min, uclamp_eff_value(p, UCLAMP_MIN));
-
-			/*
-			 * If there is no active max uclamp constraint,
-			 * directly use task's one, otherwise keep max.
-			 */
-			if (uclamp_rq_is_idle(cpu_rq(cpu)))
-				max = uclamp_eff_value(p, UCLAMP_MAX);
-			else
-				max = max(max, uclamp_eff_value(p, UCLAMP_MAX));
-		}
-
-		eff_util = sugov_effective_cpu_perf(cpu, eff_util, min, max);
-		max_util = max(max_util, eff_util);
-	}
-
-	return min(max_util, eenv->cpu_cap);
-}
-
-/*
- * compute_energy(): Use the Energy Model to estimate the energy that @pd would
- * consume for a given utilization landscape @eenv. When @dst_cpu < 0, the task
- * contribution is ignored.
- */
-static inline unsigned long
-compute_energy(struct energy_env *eenv, struct perf_domain *pd,
-	       struct cpumask *pd_cpus, struct task_struct *p, int dst_cpu)
-{
-	unsigned long max_util = eenv_pd_max_util(eenv, pd_cpus, p, dst_cpu);
-	unsigned long busy_time = eenv->pd_busy_time;
-	unsigned long energy;
-
-	if (dst_cpu >= 0)
-		busy_time = min(eenv->pd_cap, busy_time + eenv->task_busy_time);
-
-	energy = em_cpu_energy(pd->em_pd, max_util, busy_time, eenv->cpu_cap);
-
-	trace_sched_compute_energy_tp(p, dst_cpu, energy, max_util, busy_time);
-
-	return energy;
-}
-
-/*
- * find_energy_efficient_cpu(): Find most energy-efficient target CPU for the
- * waking task. find_energy_efficient_cpu() looks for the CPU with maximum
- * spare capacity in each performance domain and uses it as a potential
- * candidate to execute the task. Then, it uses the Energy Model to figure
- * out which of the CPU candidates is the most energy-efficient.
- *
- * The rationale for this heuristic is as follows. In a performance domain,
- * all the most energy efficient CPU candidates (according to the Energy
- * Model) are those for which we'll request a low frequency. When there are
- * several CPUs for which the frequency request will be the same, we don't
- * have enough data to break the tie between them, because the Energy Model
- * only includes active power costs. With this model, if we assume that
- * frequency requests follow utilization (e.g. using schedutil), the CPU with
- * the maximum spare capacity in a performance domain is guaranteed to be among
- * the best candidates of the performance domain.
- *
- * In practice, it could be preferable from an energy standpoint to pack
- * small tasks on a CPU in order to let other CPUs go in deeper idle states,
- * but that could also hurt our chances to go cluster idle, and we have no
- * ways to tell with the current Energy Model if this is actually a good
- * idea or not. So, find_energy_efficient_cpu() basically favors
- * cluster-packing, and spreading inside a cluster. That should at least be
- * a good thing for latency, and this is consistent with the idea that most
- * of the energy savings of EAS come from the asymmetry of the system, and
- * not so much from breaking the tie between identical CPUs. That's also the
- * reason why EAS is enabled in the topology code only for systems where
- * SD_ASYM_CPUCAPACITY is set.
- *
- * NOTE: Forkees are not accepted in the energy-aware wake-up path because
- * they don't have any useful utilization data yet and it's not possible to
- * forecast their impact on energy consumption. Consequently, they will be
- * placed by sched_balance_find_dst_cpu() on the least loaded CPU, which might turn out
- * to be energy-inefficient in some use-cases. The alternative would be to
- * bias new tasks towards specific types of CPUs first, or to try to infer
- * their util_avg from the parent task, but those heuristics could hurt
- * other use-cases too. So, until someone finds a better way to solve this,
- * let's keep things simple by re-using the existing slow path.
- */
-static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
-{
-	struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
-	unsigned long prev_delta = ULONG_MAX, best_delta = ULONG_MAX;
-	unsigned long p_util_min = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MIN) : 0;
-	unsigned long p_util_max = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MAX) : 1024;
-	struct root_domain *rd = this_rq()->rd;
-	int cpu, best_energy_cpu, target = -1;
-	int prev_fits = -1, best_fits = -1;
-	unsigned long best_thermal_cap = 0;
-	unsigned long prev_thermal_cap = 0;
-	struct sched_domain *sd;
-	struct perf_domain *pd;
-	struct energy_env eenv;
-
-	rcu_read_lock();
-	pd = rcu_dereference(rd->pd);
-	if (!pd)
-		goto unlock;
-
-	/*
-	 * Energy-aware wake-up happens on the lowest sched_domain starting
-	 * from sd_asym_cpucapacity spanning over this_cpu and prev_cpu.
-	 */
-	sd = rcu_dereference(*this_cpu_ptr(&sd_asym_cpucapacity));
-	while (sd && !cpumask_test_cpu(prev_cpu, sched_domain_span(sd)))
-		sd = sd->parent;
-	if (!sd)
-		goto unlock;
-
-	target = prev_cpu;
-
-	sync_entity_load_avg(&p->se);
-	if (!task_util_est(p) && p_util_min == 0)
-		goto unlock;
-
-	eenv_task_busy_time(&eenv, p, prev_cpu);
-
-	for (; pd; pd = pd->next) {
-		unsigned long util_min = p_util_min, util_max = p_util_max;
-		unsigned long cpu_cap, cpu_thermal_cap, util;
-		long prev_spare_cap = -1, max_spare_cap = -1;
-		unsigned long rq_util_min, rq_util_max;
-		unsigned long cur_delta, base_energy;
-		int max_spare_cap_cpu = -1;
-		int fits, max_fits = -1;
-
-		cpumask_and(cpus, perf_domain_span(pd), cpu_online_mask);
-
-		if (cpumask_empty(cpus))
-			continue;
-
-		/* Account thermal pressure for the energy estimation */
-		cpu = cpumask_first(cpus);
-		cpu_thermal_cap = arch_scale_cpu_capacity(cpu);
-		cpu_thermal_cap -= arch_scale_thermal_pressure(cpu);
-
-		eenv.cpu_cap = cpu_thermal_cap;
-		eenv.pd_cap = 0;
-
-		for_each_cpu(cpu, cpus) {
-			struct rq *rq = cpu_rq(cpu);
-
-			eenv.pd_cap += cpu_thermal_cap;
-
-			if (!cpumask_test_cpu(cpu, sched_domain_span(sd)))
-				continue;
-
-			if (!cpumask_test_cpu(cpu, p->cpus_ptr))
-				continue;
-
-			util = cpu_util(cpu, p, cpu, 0);
-			cpu_cap = capacity_of(cpu);
-
-			/*
-			 * Skip CPUs that cannot satisfy the capacity request.
-			 * IOW, placing the task there would make the CPU
-			 * overutilized. Take uclamp into account to see how
-			 * much capacity we can get out of the CPU; this is
-			 * aligned with sched_cpu_util().
-			 */
-			if (uclamp_is_used() && !uclamp_rq_is_idle(rq)) {
-				/*
-				 * Open code uclamp_rq_util_with() except for
-				 * the clamp() part. I.e.: apply max aggregation
-				 * only. util_fits_cpu() logic requires to
-				 * operate on non clamped util but must use the
-				 * max-aggregated uclamp_{min, max}.
-				 */
-				rq_util_min = uclamp_rq_get(rq, UCLAMP_MIN);
-				rq_util_max = uclamp_rq_get(rq, UCLAMP_MAX);
-
-				util_min = max(rq_util_min, p_util_min);
-				util_max = max(rq_util_max, p_util_max);
-			}
-
-			fits = util_fits_cpu(util, util_min, util_max, cpu);
-			if (!fits)
-				continue;
-
-			lsub_positive(&cpu_cap, util);
-
-			if (cpu == prev_cpu) {
-				/* Always use prev_cpu as a candidate. */
-				prev_spare_cap = cpu_cap;
-				prev_fits = fits;
-			} else if ((fits > max_fits) ||
-				   ((fits == max_fits) && ((long)cpu_cap > max_spare_cap))) {
-				/*
-				 * Find the CPU with the maximum spare capacity
-				 * among the remaining CPUs in the performance
-				 * domain.
-				 */
-				max_spare_cap = cpu_cap;
-				max_spare_cap_cpu = cpu;
-				max_fits = fits;
-			}
-		}
-
-		if (max_spare_cap_cpu < 0 && prev_spare_cap < 0)
-			continue;
-
-		eenv_pd_busy_time(&eenv, cpus, p);
-		/* Compute the 'base' energy of the pd, without @p */
-		base_energy = compute_energy(&eenv, pd, cpus, p, -1);
-
-		/* Evaluate the energy impact of using prev_cpu. */
-		if (prev_spare_cap > -1) {
-			prev_delta = compute_energy(&eenv, pd, cpus, p,
-						    prev_cpu);
-			/* CPU utilization has changed */
-			if (prev_delta < base_energy)
-				goto unlock;
-			prev_delta -= base_energy;
-			prev_thermal_cap = cpu_thermal_cap;
-			best_delta = min(best_delta, prev_delta);
-		}
-
-		/* Evaluate the energy impact of using max_spare_cap_cpu. */
-		if (max_spare_cap_cpu >= 0 && max_spare_cap > prev_spare_cap) {
-			/* Current best energy cpu fits better */
-			if (max_fits < best_fits)
-				continue;
-
-			/*
-			 * Both don't fit performance hint (i.e. uclamp_min)
-			 * but best energy cpu has better capacity.
-			 */
-			if ((max_fits < 0) &&
-			    (cpu_thermal_cap <= best_thermal_cap))
-				continue;
-
-			cur_delta = compute_energy(&eenv, pd, cpus, p,
-						   max_spare_cap_cpu);
-			/* CPU utilization has changed */
-			if (cur_delta < base_energy)
-				goto unlock;
-			cur_delta -= base_energy;
-
-			/*
-			 * Both fit for the task but best energy cpu has lower
-			 * energy impact.
-			 */
-			if ((max_fits > 0) && (best_fits > 0) &&
-			    (cur_delta >= best_delta))
-				continue;
-
-			best_delta = cur_delta;
-			best_energy_cpu = max_spare_cap_cpu;
-			best_fits = max_fits;
-			best_thermal_cap = cpu_thermal_cap;
-		}
-	}
-	rcu_read_unlock();
-
-	if ((best_fits > prev_fits) ||
-	    ((best_fits > 0) && (best_delta < prev_delta)) ||
-	    ((best_fits < 0) && (best_thermal_cap > prev_thermal_cap)))
-		target = best_energy_cpu;
-
-	return target;
-
-unlock:
-	rcu_read_unlock();
-
-	return target;
-}
-
-/*
- * select_task_rq_fair: Select target runqueue for the waking task in domains
- * that have the relevant SD flag set. In practice, this is SD_BALANCE_WAKE,
- * SD_BALANCE_FORK, or SD_BALANCE_EXEC.
- *
- * Balances load by selecting the idlest CPU in the idlest group, or under
- * certain conditions an idle sibling CPU if the domain has SD_WAKE_AFFINE set.
- *
- * Returns the target CPU number.
- */
-static int
-select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags)
-{
-	int sync = (wake_flags & WF_SYNC) && !(current->flags & PF_EXITING);
-	struct sched_domain *tmp, *sd = NULL;
-	int cpu = smp_processor_id();
-	int new_cpu = prev_cpu;
-	int want_affine = 0;
-	/* SD_flags and WF_flags share the first nibble */
-	int sd_flag = wake_flags & 0xF;
-
-	/*
-	 * required for stable ->cpus_allowed
-	 */
-	lockdep_assert_held(&p->pi_lock);
-	if (wake_flags & WF_TTWU) {
-		record_wakee(p);
-
-		if ((wake_flags & WF_CURRENT_CPU) &&
-		    cpumask_test_cpu(cpu, p->cpus_ptr))
-			return cpu;
-
-		if (!is_rd_overutilized(this_rq()->rd)) {
-			new_cpu = find_energy_efficient_cpu(p, prev_cpu);
-			if (new_cpu >= 0)
-				return new_cpu;
-			new_cpu = prev_cpu;
-		}
-
-		want_affine = !wake_wide(p) && cpumask_test_cpu(cpu, p->cpus_ptr);
-	}
-
-	rcu_read_lock();
-	for_each_domain(cpu, tmp) {
-		/*
-		 * If both 'cpu' and 'prev_cpu' are part of this domain,
-		 * cpu is a valid SD_WAKE_AFFINE target.
-		 */
-		if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
-		    cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
-			if (cpu != prev_cpu)
-				new_cpu = wake_affine(tmp, p, cpu, prev_cpu, sync);
-
-			sd = NULL; /* Prefer wake_affine over balance flags */
-			break;
-		}
-
-		/*
-		 * Usually only true for WF_EXEC and WF_FORK, as sched_domains
-		 * usually do not have SD_BALANCE_WAKE set. That means wakeup
-		 * will usually go to the fast path.
-		 */
-		if (tmp->flags & sd_flag)
-			sd = tmp;
-		else if (!want_affine)
-			break;
-	}
-
-	if (unlikely(sd)) {
-		/* Slow path */
-		new_cpu = sched_balance_find_dst_cpu(sd, p, cpu, prev_cpu, sd_flag);
-	} else if (wake_flags & WF_TTWU) { /* XXX always ? */
-		/* Fast path */
-		new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);
-	}
-	rcu_read_unlock();
-
-	return new_cpu;
-}
-
-/*
- * Called immediately before a task is migrated to a new CPU; task_cpu(p) and
- * cfs_rq_of(p) references at time of call are still valid and identify the
- * previous CPU. The caller guarantees p->pi_lock or task_rq(p)->lock is held.
- */
-static void migrate_task_rq_fair(struct task_struct *p, int new_cpu)
-{
-	struct sched_entity *se = &p->se;
-
-	if (!task_on_rq_migrating(p)) {
-		remove_entity_load_avg(se);
-
-		/*
-		 * Here, the task's PELT values have been updated according to
-		 * the current rq's clock. But if that clock hasn't been
-		 * updated in a while, a substantial idle time will be missed,
-		 * leading to an inflation after wake-up on the new rq.
-		 *
-		 * Estimate the missing time from the cfs_rq last_update_time
-		 * and update sched_avg to improve the PELT continuity after
-		 * migration.
-		 */
-		migrate_se_pelt_lag(se);
-	}
-
-	/* Tell new CPU we are migrated */
-	se->avg.last_update_time = 0;
-
-	update_scan_period(p, new_cpu);
-}
-
-static void task_dead_fair(struct task_struct *p)
-{
-	remove_entity_load_avg(&p->se);
-}
-
-/*
- * Set the max capacity the task is allowed to run at for misfit detection.
- */
-static void set_task_max_allowed_capacity(struct task_struct *p)
-{
-	struct asym_cap_data *entry;
-
-	if (!sched_asym_cpucap_active())
-		return;
-
-	rcu_read_lock();
-	list_for_each_entry_rcu(entry, &asym_cap_list, link) {
-		cpumask_t *cpumask;
-
-		cpumask = cpu_capacity_span(entry);
-		if (!cpumask_intersects(p->cpus_ptr, cpumask))
-			continue;
-
-		p->max_allowed_capacity = entry->capacity;
-		break;
-	}
-	rcu_read_unlock();
-}
-
-static void set_cpus_allowed_fair(struct task_struct *p, struct affinity_context *ctx)
-{
-	set_cpus_allowed_common(p, ctx);
-	set_task_max_allowed_capacity(p);
-}
-
-static int
-balance_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
-{
-	if (rq->nr_running)
-		return 1;
-
-	return sched_balance_newidle(rq, rf) != 0;
-}
-#else
-static inline void set_task_max_allowed_capacity(struct task_struct *p) {}
-#endif /* CONFIG_SMP */
-
-static void set_next_buddy(struct sched_entity *se)
-{
-	for_each_sched_entity(se) {
-		if (SCHED_WARN_ON(!se->on_rq))
-			return;
-		if (se_is_idle(se))
-			return;
-		cfs_rq_of(se)->next = se;
-	}
-}
-
-/*
- * Preempt the current task with a newly woken task if needed:
- */
-static void check_preempt_wakeup_fair(struct rq *rq, struct task_struct *p, int wake_flags)
-{
-	struct task_struct *curr = rq->curr;
-	struct sched_entity *se = &curr->se, *pse = &p->se;
-	struct cfs_rq *cfs_rq = task_cfs_rq(curr);
-	int cse_is_idle, pse_is_idle;
-
-	if (unlikely(se == pse))
-		return;
-
-	/*
-	 * This is possible from callers such as attach_tasks(), in which we
-	 * unconditionally wakeup_preempt() after an enqueue (which may have
-	 * lead to a throttle).  This both saves work and prevents false
-	 * next-buddy nomination below.
-	 */
-	if (unlikely(throttled_hierarchy(cfs_rq_of(pse))))
-		return;
-
-	if (sched_feat(NEXT_BUDDY) && !(wake_flags & WF_FORK)) {
-		set_next_buddy(pse);
-	}
-
-	/*
-	 * We can come here with TIF_NEED_RESCHED already set from new task
-	 * wake up path.
-	 *
-	 * Note: this also catches the edge-case of curr being in a throttled
-	 * group (e.g. via set_curr_task), since update_curr() (in the
-	 * enqueue of curr) will have resulted in resched being set.  This
-	 * prevents us from potentially nominating it as a false LAST_BUDDY
-	 * below.
-	 */
-	if (test_tsk_need_resched(curr))
-		return;
-
-	/* Idle tasks are by definition preempted by non-idle tasks. */
-	if (unlikely(task_has_idle_policy(curr)) &&
-	    likely(!task_has_idle_policy(p)))
-		goto preempt;
-
-	/*
-	 * Batch and idle tasks do not preempt non-idle tasks (their preemption
-	 * is driven by the tick):
-	 */
-	if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION))
-		return;
-
-	find_matching_se(&se, &pse);
-	WARN_ON_ONCE(!pse);
-
-	cse_is_idle = se_is_idle(se);
-	pse_is_idle = se_is_idle(pse);
-
-	/*
-	 * Preempt an idle group in favor of a non-idle group (and don't preempt
-	 * in the inverse case).
-	 */
-	if (cse_is_idle && !pse_is_idle)
-		goto preempt;
-	if (cse_is_idle != pse_is_idle)
-		return;
-
-	cfs_rq = cfs_rq_of(se);
-	update_curr(cfs_rq);
-
-	/*
-	 * XXX pick_eevdf(cfs_rq) != se ?
-	 */
-	if (pick_eevdf(cfs_rq) == pse)
-		goto preempt;
-
-	return;
-
-preempt:
-	resched_curr(rq);
-}
-
-#ifdef CONFIG_SMP
-static struct task_struct *pick_task_fair(struct rq *rq)
-{
-	struct sched_entity *se;
-	struct cfs_rq *cfs_rq;
-
-again:
-	cfs_rq = &rq->cfs;
-	if (!cfs_rq->nr_running)
-		return NULL;
-
-	do {
-		struct sched_entity *curr = cfs_rq->curr;
-
-		/* When we pick for a remote RQ, we'll not have done put_prev_entity() */
-		if (curr) {
-			if (curr->on_rq)
-				update_curr(cfs_rq);
-			else
-				curr = NULL;
-
-			if (unlikely(check_cfs_rq_runtime(cfs_rq)))
-				goto again;
-		}
-
-		se = pick_next_entity(cfs_rq);
-		cfs_rq = group_cfs_rq(se);
-	} while (cfs_rq);
-
-	return task_of(se);
-}
-#endif
-
-struct task_struct *
-pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
-{
-	struct cfs_rq *cfs_rq = &rq->cfs;
-	struct sched_entity *se;
-	struct task_struct *p;
-	int new_tasks;
-
-again:
-	if (!sched_fair_runnable(rq))
-		goto idle;
-
-#ifdef CONFIG_FAIR_GROUP_SCHED
-	if (!prev || prev->sched_class != &fair_sched_class)
-		goto simple;
-
-	/*
-	 * Because of the set_next_buddy() in dequeue_task_fair() it is rather
-	 * likely that a next task is from the same cgroup as the current.
-	 *
-	 * Therefore attempt to avoid putting and setting the entire cgroup
-	 * hierarchy, only change the part that actually changes.
-	 */
-
-	do {
-		struct sched_entity *curr = cfs_rq->curr;
-
-		/*
-		 * Since we got here without doing put_prev_entity() we also
-		 * have to consider cfs_rq->curr. If it is still a runnable
-		 * entity, update_curr() will update its vruntime, otherwise
-		 * forget we've ever seen it.
-		 */
-		if (curr) {
-			if (curr->on_rq)
-				update_curr(cfs_rq);
-			else
-				curr = NULL;
-
-			/*
-			 * This call to check_cfs_rq_runtime() will do the
-			 * throttle and dequeue its entity in the parent(s).
-			 * Therefore the nr_running test will indeed
-			 * be correct.
-			 */
-			if (unlikely(check_cfs_rq_runtime(cfs_rq))) {
-				cfs_rq = &rq->cfs;
-
-				if (!cfs_rq->nr_running)
-					goto idle;
-
-				goto simple;
-			}
-		}
-
-		se = pick_next_entity(cfs_rq);
-		cfs_rq = group_cfs_rq(se);
-	} while (cfs_rq);
-
-	p = task_of(se);
-
-	/*
-	 * Since we haven't yet done put_prev_entity and if the selected task
-	 * is a different task than we started out with, try and touch the
-	 * least amount of cfs_rqs.
-	 */
-	if (prev != p) {
-		struct sched_entity *pse = &prev->se;
-
-		while (!(cfs_rq = is_same_group(se, pse))) {
-			int se_depth = se->depth;
-			int pse_depth = pse->depth;
-
-			if (se_depth <= pse_depth) {
-				put_prev_entity(cfs_rq_of(pse), pse);
-				pse = parent_entity(pse);
-			}
-			if (se_depth >= pse_depth) {
-				set_next_entity(cfs_rq_of(se), se);
-				se = parent_entity(se);
-			}
-		}
-
-		put_prev_entity(cfs_rq, pse);
-		set_next_entity(cfs_rq, se);
-	}
-
-	goto done;
-simple:
-#endif
-	if (prev)
-		put_prev_task(rq, prev);
-
-	do {
-		se = pick_next_entity(cfs_rq);
-		set_next_entity(cfs_rq, se);
-		cfs_rq = group_cfs_rq(se);
-	} while (cfs_rq);
-
-	p = task_of(se);
-
-done: __maybe_unused;
-#ifdef CONFIG_SMP
-	/*
-	 * Move the next running task to the front of
-	 * the list, so our cfs_tasks list becomes MRU
-	 * one.
-	 */
-	list_move(&p->se.group_node, &rq->cfs_tasks);
-#endif
-
-	if (hrtick_enabled_fair(rq))
-		hrtick_start_fair(rq, p);
-
-	update_misfit_status(p, rq);
-	sched_fair_update_stop_tick(rq, p);
-
-	return p;
-
-idle:
-	if (!rf)
-		return NULL;
-
-	new_tasks = sched_balance_newidle(rq, rf);
-
-	/*
-	 * Because sched_balance_newidle() releases (and re-acquires) rq->lock, it is
-	 * possible for any higher priority task to appear. In that case we
-	 * must re-start the pick_next_entity() loop.
-	 */
-	if (new_tasks < 0)
-		return RETRY_TASK;
-
-	if (new_tasks > 0)
-		goto again;
-
-	/*
-	 * rq is about to be idle, check if we need to update the
-	 * lost_idle_time of clock_pelt
-	 */
-	update_idle_rq_clock_pelt(rq);
-
-	return NULL;
-}
-
-static struct task_struct *__pick_next_task_fair(struct rq *rq)
-{
-	return pick_next_task_fair(rq, NULL, NULL);
-}
-
-/*
- * Account for a descheduled task:
- */
-static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
-{
-	struct sched_entity *se = &prev->se;
-	struct cfs_rq *cfs_rq;
-
-	for_each_sched_entity(se) {
-		cfs_rq = cfs_rq_of(se);
-		put_prev_entity(cfs_rq, se);
-	}
-}
-
-/*
- * sched_yield() is very simple
- */
-static void yield_task_fair(struct rq *rq)
-{
-	struct task_struct *curr = rq->curr;
-	struct cfs_rq *cfs_rq = task_cfs_rq(curr);
-	struct sched_entity *se = &curr->se;
-
-	/*
-	 * Are we the only task in the tree?
-	 */
-	if (unlikely(rq->nr_running == 1))
-		return;
-
-	clear_buddies(cfs_rq, se);
-
-	update_rq_clock(rq);
-	/*
-	 * Update run-time statistics of the 'current'.
-	 */
-	update_curr(cfs_rq);
-	/*
-	 * Tell update_rq_clock() that we've just updated,
-	 * so we don't do microscopic update in schedule()
-	 * and double the fastpath cost.
-	 */
-	rq_clock_skip_update(rq);
-
-	se->deadline += calc_delta_fair(se->slice, se);
-}
-
-static bool yield_to_task_fair(struct rq *rq, struct task_struct *p)
-{
-	struct sched_entity *se = &p->se;
-
-	/* throttled hierarchies are not runnable */
-	if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se)))
-		return false;
-
-	/* Tell the scheduler that we'd really like se to run next. */
-	set_next_buddy(se);
-
-	yield_task_fair(rq);
-
-	return true;
-}
-
-#ifdef CONFIG_SMP
-/**************************************************
- * Fair scheduling class load-balancing methods.
- *
- * BASICS
- *
- * The purpose of load-balancing is to achieve the same basic fairness the
- * per-CPU scheduler provides, namely provide a proportional amount of compute
- * time to each task. This is expressed in the following equation:
- *
- *   W_i,n/P_i == W_j,n/P_j for all i,j                               (1)
- *
- * Where W_i,n is the n-th weight average for CPU i. The instantaneous weight
- * W_i,0 is defined as:
- *
- *   W_i,0 = \Sum_j w_i,j                                             (2)
- *
- * Where w_i,j is the weight of the j-th runnable task on CPU i. This weight
- * is derived from the nice value as per sched_prio_to_weight[].
- *
- * The weight average is an exponential decay average of the instantaneous
- * weight:
- *
- *   W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0               (3)
- *
- * C_i is the compute capacity of CPU i, typically it is the
- * fraction of 'recent' time available for SCHED_OTHER task execution. But it
- * can also include other factors [XXX].
- *
- * To achieve this balance we define a measure of imbalance which follows
- * directly from (1):
- *
- *   imb_i,j = max{ avg(W/C), W_i/C_i } - min{ avg(W/C), W_j/C_j }    (4)
- *
- * We them move tasks around to minimize the imbalance. In the continuous
- * function space it is obvious this converges, in the discrete case we get
- * a few fun cases generally called infeasible weight scenarios.
- *
- * [XXX expand on:
- *     - infeasible weights;
- *     - local vs global optima in the discrete case. ]
- *
- *
- * SCHED DOMAINS
- *
- * In order to solve the imbalance equation (4), and avoid the obvious O(n^2)
- * for all i,j solution, we create a tree of CPUs that follows the hardware
- * topology where each level pairs two lower groups (or better). This results
- * in O(log n) layers. Furthermore we reduce the number of CPUs going up the
- * tree to only the first of the previous level and we decrease the frequency
- * of load-balance at each level inv. proportional to the number of CPUs in
- * the groups.
- *
- * This yields:
- *
- *     log_2 n     1     n
- *   \Sum       { --- * --- * 2^i } = O(n)                            (5)
- *     i = 0      2^i   2^i
- *                               `- size of each group
- *         |         |     `- number of CPUs doing load-balance
- *         |         `- freq
- *         `- sum over all levels
- *
- * Coupled with a limit on how many tasks we can migrate every balance pass,
- * this makes (5) the runtime complexity of the balancer.
- *
- * An important property here is that each CPU is still (indirectly) connected
- * to every other CPU in at most O(log n) steps:
- *
- * The adjacency matrix of the resulting graph is given by:
- *
- *             log_2 n
- *   A_i,j = \Union     (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1)  (6)
- *             k = 0
- *
- * And you'll find that:
- *
- *   A^(log_2 n)_i,j != 0  for all i,j                                (7)
- *
- * Showing there's indeed a path between every CPU in at most O(log n) steps.
- * The task movement gives a factor of O(m), giving a convergence complexity
- * of:
- *
- *   O(nm log n),  n := nr_cpus, m := nr_tasks                        (8)
- *
- *
- * WORK CONSERVING
- *
- * In order to avoid CPUs going idle while there's still work to do, new idle
- * balancing is more aggressive and has the newly idle CPU iterate up the domain
- * tree itself instead of relying on other CPUs to bring it work.
- *
- * This adds some complexity to both (5) and (8) but it reduces the total idle
- * time.
- *
- * [XXX more?]
- *
- *
- * CGROUPS
- *
- * Cgroups make a horror show out of (2), instead of a simple sum we get:
- *
- *                                s_k,i
- *   W_i,0 = \Sum_j \Prod_k w_k * -----                               (9)
- *                                 S_k
- *
- * Where
- *
- *   s_k,i = \Sum_j w_i,j,k  and  S_k = \Sum_i s_k,i                 (10)
- *
- * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on CPU i.
- *
- * The big problem is S_k, its a global sum needed to compute a local (W_i)
- * property.
- *
- * [XXX write more on how we solve this.. _after_ merging pjt's patches that
- *      rewrite all of this once again.]
- */
-
-static unsigned long __read_mostly max_load_balance_interval = HZ/10;
-
-enum fbq_type { regular, remote, all };
-
-/*
- * 'group_type' describes the group of CPUs at the moment of load balancing.
- *
- * The enum is ordered by pulling priority, with the group with lowest priority
- * first so the group_type can simply be compared when selecting the busiest
- * group. See update_sd_pick_busiest().
- */
-enum group_type {
-	/* The group has spare capacity that can be used to run more tasks.  */
-	group_has_spare = 0,
-	/*
-	 * The group is fully used and the tasks don't compete for more CPU
-	 * cycles. Nevertheless, some tasks might wait before running.
-	 */
-	group_fully_busy,
-	/*
-	 * One task doesn't fit with CPU's capacity and must be migrated to a
-	 * more powerful CPU.
-	 */
-	group_misfit_task,
-	/*
-	 * Balance SMT group that's fully busy. Can benefit from migration
-	 * a task on SMT with busy sibling to another CPU on idle core.
-	 */
-	group_smt_balance,
-	/*
-	 * SD_ASYM_PACKING only: One local CPU with higher capacity is available,
-	 * and the task should be migrated to it instead of running on the
-	 * current CPU.
-	 */
-	group_asym_packing,
-	/*
-	 * The tasks' affinity constraints previously prevented the scheduler
-	 * from balancing the load across the system.
-	 */
-	group_imbalanced,
-	/*
-	 * The CPU is overloaded and can't provide expected CPU cycles to all
-	 * tasks.
-	 */
-	group_overloaded
-};
-
-enum migration_type {
-	migrate_load = 0,
-	migrate_util,
-	migrate_task,
-	migrate_misfit
-};
-
-#define LBF_ALL_PINNED	0x01
-#define LBF_NEED_BREAK	0x02
-#define LBF_DST_PINNED  0x04
-#define LBF_SOME_PINNED	0x08
-#define LBF_ACTIVE_LB	0x10
-
-struct lb_env {
-	struct sched_domain	*sd;
-
-	struct rq		*src_rq;
-	int			src_cpu;
-
-	int			dst_cpu;
-	struct rq		*dst_rq;
-
-	struct cpumask		*dst_grpmask;
-	int			new_dst_cpu;
-	enum cpu_idle_type	idle;
-	long			imbalance;
-	/* The set of CPUs under consideration for load-balancing */
-	struct cpumask		*cpus;
-
-	unsigned int		flags;
-
-	unsigned int		loop;
-	unsigned int		loop_break;
-	unsigned int		loop_max;
-
-	enum fbq_type		fbq_type;
-	enum migration_type	migration_type;
-	struct list_head	tasks;
-};
-
-/*
- * Is this task likely cache-hot:
- */
-static int task_hot(struct task_struct *p, struct lb_env *env)
-{
-	s64 delta;
-
-	lockdep_assert_rq_held(env->src_rq);
-
-	if (p->sched_class != &fair_sched_class)
-		return 0;
-
-	if (unlikely(task_has_idle_policy(p)))
-		return 0;
-
-	/* SMT siblings share cache */
-	if (env->sd->flags & SD_SHARE_CPUCAPACITY)
-		return 0;
-
-	/*
-	 * Buddy candidates are cache hot:
-	 */
-	if (sched_feat(CACHE_HOT_BUDDY) && env->dst_rq->nr_running &&
-	    (&p->se == cfs_rq_of(&p->se)->next))
-		return 1;
-
-	if (sysctl_sched_migration_cost == -1)
-		return 1;
-
-	/*
-	 * Don't migrate task if the task's cookie does not match
-	 * with the destination CPU's core cookie.
-	 */
-	if (!sched_core_cookie_match(cpu_rq(env->dst_cpu), p))
-		return 1;
+		if (!remaining) {
+			throttled = true;
+			break;
+		}
 
-	if (sysctl_sched_migration_cost == 0)
-		return 0;
+		rq_lock_irqsave(rq, &rf);
+		if (!cfs_rq_throttled(cfs_rq))
+			goto next;
 
-	delta = rq_clock_task(env->src_rq) - p->se.exec_start;
+		/* Already queued for async unthrottle */
+		if (!list_empty(&cfs_rq->throttled_csd_list))
+			goto next;
 
-	return delta < (s64)sysctl_sched_migration_cost;
-}
+		/* By the above checks, this should never be true */
+		SCHED_WARN_ON(cfs_rq->runtime_remaining > 0);
 
-#ifdef CONFIG_NUMA_BALANCING
-/*
- * Returns 1, if task migration degrades locality
- * Returns 0, if task migration improves locality i.e migration preferred.
- * Returns -1, if task migration is not affected by locality.
- */
-static int migrate_degrades_locality(struct task_struct *p, struct lb_env *env)
-{
-	struct numa_group *numa_group = rcu_dereference(p->numa_group);
-	unsigned long src_weight, dst_weight;
-	int src_nid, dst_nid, dist;
+		raw_spin_lock(&cfs_b->lock);
+		runtime = -cfs_rq->runtime_remaining + 1;
+		if (runtime > cfs_b->runtime)
+			runtime = cfs_b->runtime;
+		cfs_b->runtime -= runtime;
+		remaining = cfs_b->runtime;
+		raw_spin_unlock(&cfs_b->lock);
 
-	if (!static_branch_likely(&sched_numa_balancing))
-		return -1;
+		cfs_rq->runtime_remaining += runtime;
 
-	if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
-		return -1;
+		/* we check whether we're throttled above */
+		if (cfs_rq->runtime_remaining > 0) {
+			if (cpu_of(rq) != this_cpu) {
+				unthrottle_cfs_rq_async(cfs_rq);
+			} else {
+				/*
+				 * We currently only expect to be unthrottling
+				 * a single cfs_rq locally.
+				 */
+				SCHED_WARN_ON(!list_empty(&local_unthrottle));
+				list_add_tail(&cfs_rq->throttled_csd_list,
+					      &local_unthrottle);
+			}
+		} else {
+			throttled = true;
+		}
 
-	src_nid = cpu_to_node(env->src_cpu);
-	dst_nid = cpu_to_node(env->dst_cpu);
+next:
+		rq_unlock_irqrestore(rq, &rf);
+	}
 
-	if (src_nid == dst_nid)
-		return -1;
+	list_for_each_entry_safe(cfs_rq, tmp, &local_unthrottle,
+				 throttled_csd_list) {
+		struct rq *rq = rq_of(cfs_rq);
 
-	/* Migrating away from the preferred node is always bad. */
-	if (src_nid == p->numa_preferred_nid) {
-		if (env->src_rq->nr_running > env->src_rq->nr_preferred_running)
-			return 1;
-		else
-			return -1;
-	}
+		rq_lock_irqsave(rq, &rf);
 
-	/* Encourage migration to the preferred node. */
-	if (dst_nid == p->numa_preferred_nid)
-		return 0;
+		list_del_init(&cfs_rq->throttled_csd_list);
 
-	/* Leaving a core idle is often worse than degrading locality. */
-	if (env->idle == CPU_IDLE)
-		return -1;
+		if (cfs_rq_throttled(cfs_rq))
+			unthrottle_cfs_rq(cfs_rq);
 
-	dist = node_distance(src_nid, dst_nid);
-	if (numa_group) {
-		src_weight = group_weight(p, src_nid, dist);
-		dst_weight = group_weight(p, dst_nid, dist);
-	} else {
-		src_weight = task_weight(p, src_nid, dist);
-		dst_weight = task_weight(p, dst_nid, dist);
+		rq_unlock_irqrestore(rq, &rf);
 	}
+	SCHED_WARN_ON(!list_empty(&local_unthrottle));
 
-	return dst_weight < src_weight;
-}
+	rcu_read_unlock();
 
-#else
-static inline int migrate_degrades_locality(struct task_struct *p,
-					     struct lb_env *env)
-{
-	return -1;
+	return throttled;
 }
-#endif
 
 /*
- * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
+ * Responsible for refilling a task_group's bandwidth and unthrottling its
+ * cfs_rqs as appropriate. If there has been no activity within the last
+ * period the timer is deactivated until scheduling resumes; cfs_b->idle is
+ * used to track this state.
  */
-static
-int can_migrate_task(struct task_struct *p, struct lb_env *env)
+static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun, unsigned long flags)
 {
-	int tsk_cache_hot;
-
-	lockdep_assert_rq_held(env->src_rq);
-
-	/*
-	 * We do not migrate tasks that are:
-	 * 1) throttled_lb_pair, or
-	 * 2) cannot be migrated to this CPU due to cpus_ptr, or
-	 * 3) running (obviously), or
-	 * 4) are cache-hot on their current CPU.
-	 */
-	if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))
-		return 0;
-
-	/* Disregard percpu kthreads; they are where they need to be. */
-	if (kthread_is_per_cpu(p))
-		return 0;
+	int throttled;
 
-	if (!cpumask_test_cpu(env->dst_cpu, p->cpus_ptr)) {
-		int cpu;
+	/* no need to continue the timer with no bandwidth constraint */
+	if (cfs_b->quota == RUNTIME_INF)
+		goto out_deactivate;
 
-		schedstat_inc(p->stats.nr_failed_migrations_affine);
+	throttled = !list_empty(&cfs_b->throttled_cfs_rq);
+	cfs_b->nr_periods += overrun;
 
-		env->flags |= LBF_SOME_PINNED;
+	/* Refill extra burst quota even if cfs_b->idle */
+	__refill_cfs_bandwidth_runtime(cfs_b);
 
-		/*
-		 * Remember if this task can be migrated to any other CPU in
-		 * our sched_group. We may want to revisit it if we couldn't
-		 * meet load balance goals by pulling other tasks on src_cpu.
-		 *
-		 * Avoid computing new_dst_cpu
-		 * - for NEWLY_IDLE
-		 * - if we have already computed one in current iteration
-		 * - if it's an active balance
-		 */
-		if (env->idle == CPU_NEWLY_IDLE ||
-		    env->flags & (LBF_DST_PINNED | LBF_ACTIVE_LB))
-			return 0;
-
-		/* Prevent to re-select dst_cpu via env's CPUs: */
-		for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) {
-			if (cpumask_test_cpu(cpu, p->cpus_ptr)) {
-				env->flags |= LBF_DST_PINNED;
-				env->new_dst_cpu = cpu;
-				break;
-			}
-		}
+	/*
+	 * idle depends on !throttled (for the case of a large deficit), and if
+	 * we're going inactive then everything else can be deferred
+	 */
+	if (cfs_b->idle && !throttled)
+		goto out_deactivate;
 
+	if (!throttled) {
+		/* mark as potentially idle for the upcoming period */
+		cfs_b->idle = 1;
 		return 0;
 	}
 
-	/* Record that we found at least one task that could run on dst_cpu */
-	env->flags &= ~LBF_ALL_PINNED;
+	/* account preceding periods in which throttling occurred */
+	cfs_b->nr_throttled += overrun;
 
-	if (task_on_cpu(env->src_rq, p)) {
-		schedstat_inc(p->stats.nr_failed_migrations_running);
-		return 0;
+	/*
+	 * This check is repeated as we release cfs_b->lock while we unthrottle.
+	 */
+	while (throttled && cfs_b->runtime > 0) {
+		raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
+		/* we can't nest cfs_b->lock while distributing bandwidth */
+		throttled = distribute_cfs_runtime(cfs_b);
+		raw_spin_lock_irqsave(&cfs_b->lock, flags);
 	}
 
 	/*
-	 * Aggressive migration if:
-	 * 1) active balance
-	 * 2) destination numa is preferred
-	 * 3) task is cache cold, or
-	 * 4) too many balance attempts have failed.
+	 * While we are ensured activity in the period following an
+	 * unthrottle, this also covers the case in which the new bandwidth is
+	 * insufficient to cover the existing bandwidth deficit.  (Forcing the
+	 * timer to remain active while there are any throttled entities.)
 	 */
-	if (env->flags & LBF_ACTIVE_LB)
-		return 1;
-
-	tsk_cache_hot = migrate_degrades_locality(p, env);
-	if (tsk_cache_hot == -1)
-		tsk_cache_hot = task_hot(p, env);
-
-	if (tsk_cache_hot <= 0 ||
-	    env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
-		if (tsk_cache_hot == 1) {
-			schedstat_inc(env->sd->lb_hot_gained[env->idle]);
-			schedstat_inc(p->stats.nr_forced_migrations);
-		}
-		return 1;
-	}
+	cfs_b->idle = 0;
 
-	schedstat_inc(p->stats.nr_failed_migrations_hot);
 	return 0;
-}
-
-/*
- * detach_task() -- detach the task for the migration specified in env
- */
-static void detach_task(struct task_struct *p, struct lb_env *env)
-{
-	lockdep_assert_rq_held(env->src_rq);
 
-	deactivate_task(env->src_rq, p, DEQUEUE_NOCLOCK);
-	set_task_cpu(p, env->dst_cpu);
+out_deactivate:
+	return 1;
 }
 
+/* a cfs_rq won't donate quota below this amount */
+static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC;
+/* minimum remaining period time to redistribute slack quota */
+static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC;
+/* how long we wait to gather additional slack before distributing */
+static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC;
+
 /*
- * detach_one_task() -- tries to dequeue exactly one task from env->src_rq, as
- * part of active balancing operations within "domain".
+ * Are we near the end of the current quota period?
  *
- * Returns a task if successful and NULL otherwise.
+ * Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the
+ * hrtimer base being cleared by hrtimer_start. In the case of
+ * migrate_hrtimers, base is never cleared, so we are fine.
  */
-static struct task_struct *detach_one_task(struct lb_env *env)
+static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
 {
-	struct task_struct *p;
-
-	lockdep_assert_rq_held(env->src_rq);
+	struct hrtimer *refresh_timer = &cfs_b->period_timer;
+	s64 remaining;
 
-	list_for_each_entry_reverse(p,
-			&env->src_rq->cfs_tasks, se.group_node) {
-		if (!can_migrate_task(p, env))
-			continue;
+	/* if the call-back is running a quota refresh is already occurring */
+	if (hrtimer_callback_running(refresh_timer))
+		return 1;
 
-		detach_task(p, env);
+	/* is a quota refresh about to occur? */
+	remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
+	if (remaining < (s64)min_expire)
+		return 1;
 
-		/*
-		 * Right now, this is only the second place where
-		 * lb_gained[env->idle] is updated (other is detach_tasks)
-		 * so we can safely collect stats here rather than
-		 * inside detach_tasks().
-		 */
-		schedstat_inc(env->sd->lb_gained[env->idle]);
-		return p;
-	}
-	return NULL;
+	return 0;
 }
 
-/*
- * detach_tasks() -- tries to detach up to imbalance load/util/tasks from
- * busiest_rq, as part of a balancing operation within domain "sd".
- *
- * Returns number of detached tasks if successful and 0 otherwise.
- */
-static int detach_tasks(struct lb_env *env)
+static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b)
 {
-	struct list_head *tasks = &env->src_rq->cfs_tasks;
-	unsigned long util, load;
-	struct task_struct *p;
-	int detached = 0;
-
-	lockdep_assert_rq_held(env->src_rq);
-
-	/*
-	 * Source run queue has been emptied by another CPU, clear
-	 * LBF_ALL_PINNED flag as we will not test any task.
-	 */
-	if (env->src_rq->nr_running <= 1) {
-		env->flags &= ~LBF_ALL_PINNED;
-		return 0;
-	}
-
-	if (env->imbalance <= 0)
-		return 0;
-
-	while (!list_empty(tasks)) {
-		/*
-		 * We don't want to steal all, otherwise we may be treated likewise,
-		 * which could at worst lead to a livelock crash.
-		 */
-		if (env->idle && env->src_rq->nr_running <= 1)
-			break;
-
-		env->loop++;
-		/*
-		 * We've more or less seen every task there is, call it quits
-		 * unless we haven't found any movable task yet.
-		 */
-		if (env->loop > env->loop_max &&
-		    !(env->flags & LBF_ALL_PINNED))
-			break;
-
-		/* take a breather every nr_migrate tasks */
-		if (env->loop > env->loop_break) {
-			env->loop_break += SCHED_NR_MIGRATE_BREAK;
-			env->flags |= LBF_NEED_BREAK;
-			break;
-		}
-
-		p = list_last_entry(tasks, struct task_struct, se.group_node);
-
-		if (!can_migrate_task(p, env))
-			goto next;
-
-		switch (env->migration_type) {
-		case migrate_load:
-			/*
-			 * Depending of the number of CPUs and tasks and the
-			 * cgroup hierarchy, task_h_load() can return a null
-			 * value. Make sure that env->imbalance decreases
-			 * otherwise detach_tasks() will stop only after
-			 * detaching up to loop_max tasks.
-			 */
-			load = max_t(unsigned long, task_h_load(p), 1);
-
-			if (sched_feat(LB_MIN) &&
-			    load < 16 && !env->sd->nr_balance_failed)
-				goto next;
-
-			/*
-			 * Make sure that we don't migrate too much load.
-			 * Nevertheless, let relax the constraint if
-			 * scheduler fails to find a good waiting task to
-			 * migrate.
-			 */
-			if (shr_bound(load, env->sd->nr_balance_failed) > env->imbalance)
-				goto next;
-
-			env->imbalance -= load;
-			break;
-
-		case migrate_util:
-			util = task_util_est(p);
-
-			if (shr_bound(util, env->sd->nr_balance_failed) > env->imbalance)
-				goto next;
-
-			env->imbalance -= util;
-			break;
-
-		case migrate_task:
-			env->imbalance--;
-			break;
+	u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration;
 
-		case migrate_misfit:
-			/* This is not a misfit task */
-			if (task_fits_cpu(p, env->src_cpu))
-				goto next;
+	/* if there's a quota refresh soon don't bother with slack */
+	if (runtime_refresh_within(cfs_b, min_left))
+		return;
 
-			env->imbalance = 0;
-			break;
-		}
+	/* don't push forwards an existing deferred unthrottle */
+	if (cfs_b->slack_started)
+		return;
+	cfs_b->slack_started = true;
 
-		detach_task(p, env);
-		list_add(&p->se.group_node, &env->tasks);
+	hrtimer_start(&cfs_b->slack_timer,
+			ns_to_ktime(cfs_bandwidth_slack_period),
+			HRTIMER_MODE_REL);
+}
 
-		detached++;
+/* we know any runtime found here is valid as update_curr() precedes return */
+static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
+{
+	struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
+	s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime;
 
-#ifdef CONFIG_PREEMPTION
-		/*
-		 * NEWIDLE balancing is a source of latency, so preemptible
-		 * kernels will stop after the first task is detached to minimize
-		 * the critical section.
-		 */
-		if (env->idle == CPU_NEWLY_IDLE)
-			break;
-#endif
+	if (slack_runtime <= 0)
+		return;
 
-		/*
-		 * We only want to steal up to the prescribed amount of
-		 * load/util/tasks.
-		 */
-		if (env->imbalance <= 0)
-			break;
+	raw_spin_lock(&cfs_b->lock);
+	if (cfs_b->quota != RUNTIME_INF) {
+		cfs_b->runtime += slack_runtime;
 
-		continue;
-next:
-		list_move(&p->se.group_node, tasks);
+		/* we are under rq->lock, defer unthrottling using a timer */
+		if (cfs_b->runtime > sched_cfs_bandwidth_slice() &&
+		    !list_empty(&cfs_b->throttled_cfs_rq))
+			start_cfs_slack_bandwidth(cfs_b);
 	}
+	raw_spin_unlock(&cfs_b->lock);
 
-	/*
-	 * Right now, this is one of only two places we collect this stat
-	 * so we can safely collect detach_one_task() stats here rather
-	 * than inside detach_one_task().
-	 */
-	schedstat_add(env->sd->lb_gained[env->idle], detached);
-
-	return detached;
-}
-
-/*
- * attach_task() -- attach the task detached by detach_task() to its new rq.
- */
-static void attach_task(struct rq *rq, struct task_struct *p)
-{
-	lockdep_assert_rq_held(rq);
-
-	WARN_ON_ONCE(task_rq(p) != rq);
-	activate_task(rq, p, ENQUEUE_NOCLOCK);
-	wakeup_preempt(rq, p, 0);
+	/* even if it's not valid for return we don't want to try again */
+	cfs_rq->runtime_remaining -= slack_runtime;
 }
 
-/*
- * attach_one_task() -- attaches the task returned from detach_one_task() to
- * its new rq.
- */
-static void attach_one_task(struct rq *rq, struct task_struct *p)
+static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
 {
-	struct rq_flags rf;
+	if (!cfs_bandwidth_used())
+		return;
 
-	rq_lock(rq, &rf);
-	update_rq_clock(rq);
-	attach_task(rq, p);
-	rq_unlock(rq, &rf);
+	if (!cfs_rq->runtime_enabled || cfs_rq->nr_running)
+		return;
+
+	__return_cfs_rq_runtime(cfs_rq);
 }
 
 /*
- * attach_tasks() -- attaches all tasks detached by detach_tasks() to their
- * new rq.
+ * This is done with a timer (instead of inline with bandwidth return) since
+ * it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
  */
-static void attach_tasks(struct lb_env *env)
+static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
 {
-	struct list_head *tasks = &env->tasks;
-	struct task_struct *p;
-	struct rq_flags rf;
-
-	rq_lock(env->dst_rq, &rf);
-	update_rq_clock(env->dst_rq);
+	u64 runtime = 0, slice = sched_cfs_bandwidth_slice();
+	unsigned long flags;
 
-	while (!list_empty(tasks)) {
-		p = list_first_entry(tasks, struct task_struct, se.group_node);
-		list_del_init(&p->se.group_node);
+	/* confirm we're still not at a refresh boundary */
+	raw_spin_lock_irqsave(&cfs_b->lock, flags);
+	cfs_b->slack_started = false;
 
-		attach_task(env->dst_rq, p);
+	if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) {
+		raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
+		return;
 	}
 
-	rq_unlock(env->dst_rq, &rf);
-}
+	if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice)
+		runtime = cfs_b->runtime;
 
-#ifdef CONFIG_NO_HZ_COMMON
-static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq)
-{
-	if (cfs_rq->avg.load_avg)
-		return true;
+	raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
 
-	if (cfs_rq->avg.util_avg)
-		return true;
+	if (!runtime)
+		return;
 
-	return false;
+	distribute_cfs_runtime(cfs_b);
 }
 
-static inline bool others_have_blocked(struct rq *rq)
+/*
+ * When a group wakes up we want to make sure that its quota is not already
+ * expired/exceeded, otherwise it may be allowed to steal additional ticks of
+ * runtime as update_curr() throttling can not trigger until it's on-rq.
+ */
+static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
 {
-	if (cpu_util_rt(rq))
-		return true;
-
-	if (cpu_util_dl(rq))
-		return true;
+	if (!cfs_bandwidth_used())
+		return;
 
-	if (thermal_load_avg(rq))
-		return true;
+	/* an active group must be handled by the update_curr()->put() path */
+	if (!cfs_rq->runtime_enabled || cfs_rq->curr)
+		return;
 
-	if (cpu_util_irq(rq))
-		return true;
+	/* ensure the group is not already throttled */
+	if (cfs_rq_throttled(cfs_rq))
+		return;
 
-	return false;
+	/* update runtime allocation */
+	account_cfs_rq_runtime(cfs_rq, 0);
+	if (cfs_rq->runtime_remaining <= 0)
+		throttle_cfs_rq(cfs_rq);
 }
 
-static inline void update_blocked_load_tick(struct rq *rq)
+static void sync_throttle(struct task_group *tg, int cpu)
 {
-	WRITE_ONCE(rq->last_blocked_load_update_tick, jiffies);
-}
+	struct cfs_rq *pcfs_rq, *cfs_rq;
 
-static inline void update_blocked_load_status(struct rq *rq, bool has_blocked)
-{
-	if (!has_blocked)
-		rq->has_blocked_load = 0;
+	if (!cfs_bandwidth_used())
+		return;
+
+	if (!tg->parent)
+		return;
+
+	cfs_rq = tg->cfs_rq[cpu];
+	pcfs_rq = tg->parent->cfs_rq[cpu];
+
+	cfs_rq->throttle_count = pcfs_rq->throttle_count;
+	cfs_rq->throttled_clock_pelt = rq_clock_pelt(cpu_rq(cpu));
 }
-#else
-static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq) { return false; }
-static inline bool others_have_blocked(struct rq *rq) { return false; }
-static inline void update_blocked_load_tick(struct rq *rq) {}
-static inline void update_blocked_load_status(struct rq *rq, bool has_blocked) {}
-#endif
 
-static bool __update_blocked_others(struct rq *rq, bool *done)
+/* conditionally throttle active cfs_rq's from put_prev_entity() */
+static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq)
 {
-	const struct sched_class *curr_class;
-	u64 now = rq_clock_pelt(rq);
-	unsigned long thermal_pressure;
-	bool decayed;
+	if (!cfs_bandwidth_used())
+		return false;
+
+	if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0))
+		return false;
 
 	/*
-	 * update_load_avg() can call cpufreq_update_util(). Make sure that RT,
-	 * DL and IRQ signals have been updated before updating CFS.
+	 * it's possible for a throttled entity to be forced into a running
+	 * state (e.g. set_curr_task), in this case we're finished.
 	 */
-	curr_class = rq->curr->sched_class;
+	if (cfs_rq_throttled(cfs_rq))
+		return true;
 
-	thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
+	return throttle_cfs_rq(cfs_rq);
+}
 
-	decayed = update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) |
-		  update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) |
-		  update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure) |
-		  update_irq_load_avg(rq, 0);
+static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer)
+{
+	struct cfs_bandwidth *cfs_b =
+		container_of(timer, struct cfs_bandwidth, slack_timer);
 
-	if (others_have_blocked(rq))
-		*done = false;
+	do_sched_cfs_slack_timer(cfs_b);
 
-	return decayed;
+	return HRTIMER_NORESTART;
 }
 
-#ifdef CONFIG_FAIR_GROUP_SCHED
+extern const u64 max_cfs_quota_period;
 
-static bool __update_blocked_fair(struct rq *rq, bool *done)
+static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)
 {
-	struct cfs_rq *cfs_rq, *pos;
-	bool decayed = false;
-	int cpu = cpu_of(rq);
-
-	/*
-	 * Iterates the task_group tree in a bottom up fashion, see
-	 * list_add_leaf_cfs_rq() for details.
-	 */
-	for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) {
-		struct sched_entity *se;
+	struct cfs_bandwidth *cfs_b =
+		container_of(timer, struct cfs_bandwidth, period_timer);
+	unsigned long flags;
+	int overrun;
+	int idle = 0;
+	int count = 0;
 
-		if (update_cfs_rq_load_avg(cfs_rq_clock_pelt(cfs_rq), cfs_rq)) {
-			update_tg_load_avg(cfs_rq);
+	raw_spin_lock_irqsave(&cfs_b->lock, flags);
+	for (;;) {
+		overrun = hrtimer_forward_now(timer, cfs_b->period);
+		if (!overrun)
+			break;
 
-			if (cfs_rq->nr_running == 0)
-				update_idle_cfs_rq_clock_pelt(cfs_rq);
+		idle = do_sched_cfs_period_timer(cfs_b, overrun, flags);
 
-			if (cfs_rq == &rq->cfs)
-				decayed = true;
-		}
+		if (++count > 3) {
+			u64 new, old = ktime_to_ns(cfs_b->period);
 
-		/* Propagate pending load changes to the parent, if any: */
-		se = cfs_rq->tg->se[cpu];
-		if (se && !skip_blocked_update(se))
-			update_load_avg(cfs_rq_of(se), se, UPDATE_TG);
+			/*
+			 * Grow period by a factor of 2 to avoid losing precision.
+			 * Precision loss in the quota/period ratio can cause __cfs_schedulable
+			 * to fail.
+			 */
+			new = old * 2;
+			if (new < max_cfs_quota_period) {
+				cfs_b->period = ns_to_ktime(new);
+				cfs_b->quota *= 2;
+				cfs_b->burst *= 2;
 
-		/*
-		 * There can be a lot of idle CPU cgroups.  Don't let fully
-		 * decayed cfs_rqs linger on the list.
-		 */
-		if (cfs_rq_is_decayed(cfs_rq))
-			list_del_leaf_cfs_rq(cfs_rq);
+				pr_warn_ratelimited(
+	"cfs_period_timer[cpu%d]: period too short, scaling up (new cfs_period_us = %lld, cfs_quota_us = %lld)\n",
+					smp_processor_id(),
+					div_u64(new, NSEC_PER_USEC),
+					div_u64(cfs_b->quota, NSEC_PER_USEC));
+			} else {
+				pr_warn_ratelimited(
+	"cfs_period_timer[cpu%d]: period too short, but cannot scale up without losing precision (cfs_period_us = %lld, cfs_quota_us = %lld)\n",
+					smp_processor_id(),
+					div_u64(old, NSEC_PER_USEC),
+					div_u64(cfs_b->quota, NSEC_PER_USEC));
+			}
 
-		/* Don't need periodic decay once load/util_avg are null */
-		if (cfs_rq_has_blocked(cfs_rq))
-			*done = false;
+			/* reset count so we don't come right back in here */
+			count = 0;
+		}
 	}
+	if (idle)
+		cfs_b->period_active = 0;
+	raw_spin_unlock_irqrestore(&cfs_b->lock, flags);
 
-	return decayed;
+	return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
 }
 
-/*
- * Compute the hierarchical load factor for cfs_rq and all its ascendants.
- * This needs to be done in a top-down fashion because the load of a child
- * group is a fraction of its parents load.
- */
-static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq)
+void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b, struct cfs_bandwidth *parent)
 {
-	struct rq *rq = rq_of(cfs_rq);
-	struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)];
-	unsigned long now = jiffies;
-	unsigned long load;
-
-	if (cfs_rq->last_h_load_update == now)
-		return;
-
-	WRITE_ONCE(cfs_rq->h_load_next, NULL);
-	for_each_sched_entity(se) {
-		cfs_rq = cfs_rq_of(se);
-		WRITE_ONCE(cfs_rq->h_load_next, se);
-		if (cfs_rq->last_h_load_update == now)
-			break;
-	}
+	raw_spin_lock_init(&cfs_b->lock);
+	cfs_b->runtime = 0;
+	cfs_b->quota = RUNTIME_INF;
+	cfs_b->period = ns_to_ktime(default_cfs_period());
+	cfs_b->burst = 0;
+	cfs_b->hierarchical_quota = parent ? parent->hierarchical_quota : RUNTIME_INF;
 
-	if (!se) {
-		cfs_rq->h_load = cfs_rq_load_avg(cfs_rq);
-		cfs_rq->last_h_load_update = now;
-	}
+	INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
+	hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED);
+	cfs_b->period_timer.function = sched_cfs_period_timer;
 
-	while ((se = READ_ONCE(cfs_rq->h_load_next)) != NULL) {
-		load = cfs_rq->h_load;
-		load = div64_ul(load * se->avg.load_avg,
-			cfs_rq_load_avg(cfs_rq) + 1);
-		cfs_rq = group_cfs_rq(se);
-		cfs_rq->h_load = load;
-		cfs_rq->last_h_load_update = now;
-	}
+	/* Add a random offset so that timers interleave */
+	hrtimer_set_expires(&cfs_b->period_timer,
+			    get_random_u32_below(cfs_b->period));
+	hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	cfs_b->slack_timer.function = sched_cfs_slack_timer;
+	cfs_b->slack_started = false;
 }
 
-static unsigned long task_h_load(struct task_struct *p)
+static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
 {
-	struct cfs_rq *cfs_rq = task_cfs_rq(p);
-
-	update_cfs_rq_h_load(cfs_rq);
-	return div64_ul(p->se.avg.load_avg * cfs_rq->h_load,
-			cfs_rq_load_avg(cfs_rq) + 1);
+	cfs_rq->runtime_enabled = 0;
+	INIT_LIST_HEAD(&cfs_rq->throttled_list);
+	INIT_LIST_HEAD(&cfs_rq->throttled_csd_list);
 }
-#else
-static bool __update_blocked_fair(struct rq *rq, bool *done)
-{
-	struct cfs_rq *cfs_rq = &rq->cfs;
-	bool decayed;
 
-	decayed = update_cfs_rq_load_avg(cfs_rq_clock_pelt(cfs_rq), cfs_rq);
-	if (cfs_rq_has_blocked(cfs_rq))
-		*done = false;
+void start_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
+{
+	lockdep_assert_held(&cfs_b->lock);
 
-	return decayed;
-}
+	if (cfs_b->period_active)
+		return;
 
-static unsigned long task_h_load(struct task_struct *p)
-{
-	return p->se.avg.load_avg;
+	cfs_b->period_active = 1;
+	hrtimer_forward_now(&cfs_b->period_timer, cfs_b->period);
+	hrtimer_start_expires(&cfs_b->period_timer, HRTIMER_MODE_ABS_PINNED);
 }
-#endif
 
-static void sched_balance_update_blocked_averages(int cpu)
+static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
 {
-	bool decayed = false, done = true;
-	struct rq *rq = cpu_rq(cpu);
-	struct rq_flags rf;
+	int __maybe_unused i;
 
-	rq_lock_irqsave(rq, &rf);
-	update_blocked_load_tick(rq);
-	update_rq_clock(rq);
+	/* init_cfs_bandwidth() was not called */
+	if (!cfs_b->throttled_cfs_rq.next)
+		return;
 
-	decayed |= __update_blocked_others(rq, &done);
-	decayed |= __update_blocked_fair(rq, &done);
+	hrtimer_cancel(&cfs_b->period_timer);
+	hrtimer_cancel(&cfs_b->slack_timer);
 
-	update_blocked_load_status(rq, !done);
-	if (decayed)
-		cpufreq_update_util(rq, 0);
-	rq_unlock_irqrestore(rq, &rf);
-}
+	/*
+	 * It is possible that we still have some cfs_rq's pending on a CSD
+	 * list, though this race is very rare. In order for this to occur, we
+	 * must have raced with the last task leaving the group while there
+	 * exist throttled cfs_rq(s), and the period_timer must have queued the
+	 * CSD item but the remote cpu has not yet processed it. To handle this,
+	 * we can simply flush all pending CSD work inline here. We're
+	 * guaranteed at this point that no additional cfs_rq of this group can
+	 * join a CSD list.
+	 */
+#ifdef CONFIG_SMP
+	for_each_possible_cpu(i) {
+		struct rq *rq = cpu_rq(i);
+		unsigned long flags;
 
-/********** Helpers for sched_balance_find_src_group ************************/
+		if (list_empty(&rq->cfsb_csd_list))
+			continue;
 
-/*
- * sg_lb_stats - stats of a sched_group required for load-balancing:
- */
-struct sg_lb_stats {
-	unsigned long avg_load;			/* Avg load            over the CPUs of the group */
-	unsigned long group_load;		/* Total load          over the CPUs of the group */
-	unsigned long group_capacity;		/* Capacity            over the CPUs of the group */
-	unsigned long group_util;		/* Total utilization   over the CPUs of the group */
-	unsigned long group_runnable;		/* Total runnable time over the CPUs of the group */
-	unsigned int sum_nr_running;		/* Nr of all tasks running in the group */
-	unsigned int sum_h_nr_running;		/* Nr of CFS tasks running in the group */
-	unsigned int idle_cpus;                 /* Nr of idle CPUs         in the group */
-	unsigned int group_weight;
-	enum group_type group_type;
-	unsigned int group_asym_packing;	/* Tasks should be moved to preferred CPU */
-	unsigned int group_smt_balance;		/* Task on busy SMT be moved */
-	unsigned long group_misfit_task_load;	/* A CPU has a task too big for its capacity */
-#ifdef CONFIG_NUMA_BALANCING
-	unsigned int nr_numa_running;
-	unsigned int nr_preferred_running;
+		local_irq_save(flags);
+		__cfsb_csd_unthrottle(rq);
+		local_irq_restore(flags);
+	}
 #endif
-};
+}
 
 /*
- * sd_lb_stats - stats of a sched_domain required for load-balancing:
+ * Both these CPU hotplug callbacks race against unregister_fair_sched_group()
+ *
+ * The race is harmless, since modifying bandwidth settings of unhooked group
+ * bits doesn't do much.
  */
-struct sd_lb_stats {
-	struct sched_group *busiest;		/* Busiest group in this sd */
-	struct sched_group *local;		/* Local group in this sd */
-	unsigned long total_load;		/* Total load of all groups in sd */
-	unsigned long total_capacity;		/* Total capacity of all groups in sd */
-	unsigned long avg_load;			/* Average load across all groups in sd */
-	unsigned int prefer_sibling;		/* Tasks should go to sibling first */
-
-	struct sg_lb_stats busiest_stat;	/* Statistics of the busiest group */
-	struct sg_lb_stats local_stat;		/* Statistics of the local group */
-};
 
-static inline void init_sd_lb_stats(struct sd_lb_stats *sds)
-{
-	/*
-	 * Skimp on the clearing to avoid duplicate work. We can avoid clearing
-	 * local_stat because update_sg_lb_stats() does a full clear/assignment.
-	 * We must however set busiest_stat::group_type and
-	 * busiest_stat::idle_cpus to the worst busiest group because
-	 * update_sd_pick_busiest() reads these before assignment.
-	 */
-	*sds = (struct sd_lb_stats){
-		.busiest = NULL,
-		.local = NULL,
-		.total_load = 0UL,
-		.total_capacity = 0UL,
-		.busiest_stat = {
-			.idle_cpus = UINT_MAX,
-			.group_type = group_has_spare,
-		},
-	};
+/* cpu online callback */
+static void __maybe_unused update_runtime_enabled(struct rq *rq)
+{
+	struct task_group *tg;
+
+	lockdep_assert_rq_held(rq);
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(tg, &task_groups, list) {
+		struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
+		struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
+
+		raw_spin_lock(&cfs_b->lock);
+		cfs_rq->runtime_enabled = cfs_b->quota != RUNTIME_INF;
+		raw_spin_unlock(&cfs_b->lock);
+	}
+	rcu_read_unlock();
 }
 
-static unsigned long scale_rt_capacity(int cpu)
+/* cpu offline callback */
+static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq)
 {
-	struct rq *rq = cpu_rq(cpu);
-	unsigned long max = arch_scale_cpu_capacity(cpu);
-	unsigned long used, free;
-	unsigned long irq;
-
-	irq = cpu_util_irq(rq);
+	struct task_group *tg;
 
-	if (unlikely(irq >= max))
-		return 1;
+	lockdep_assert_rq_held(rq);
 
 	/*
-	 * avg_rt.util_avg and avg_dl.util_avg track binary signals
-	 * (running and not running) with weights 0 and 1024 respectively.
-	 * avg_thermal.load_avg tracks thermal pressure and the weighted
-	 * average uses the actual delta max capacity(load).
+	 * The rq clock has already been updated in the
+	 * set_rq_offline(), so we should skip updating
+	 * the rq clock again in unthrottle_cfs_rq().
 	 */
-	used = cpu_util_rt(rq);
-	used += cpu_util_dl(rq);
-	used += thermal_load_avg(rq);
+	rq_clock_start_loop_update(rq);
 
-	if (unlikely(used >= max))
-		return 1;
+	rcu_read_lock();
+	list_for_each_entry_rcu(tg, &task_groups, list) {
+		struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
+
+		if (!cfs_rq->runtime_enabled)
+			continue;
+
+		/*
+		 * clock_task is not advancing so we just need to make sure
+		 * there's some valid quota amount
+		 */
+		cfs_rq->runtime_remaining = 1;
+		/*
+		 * Offline rq is schedulable till CPU is completely disabled
+		 * in take_cpu_down(), so we prevent new cfs throttling here.
+		 */
+		cfs_rq->runtime_enabled = 0;
 
-	free = max - used;
+		if (cfs_rq_throttled(cfs_rq))
+			unthrottle_cfs_rq(cfs_rq);
+	}
+	rcu_read_unlock();
 
-	return scale_irq_capacity(free, irq, max);
+	rq_clock_stop_loop_update(rq);
 }
 
-static void update_cpu_capacity(struct sched_domain *sd, int cpu)
+bool cfs_task_bw_constrained(struct task_struct *p)
 {
-	unsigned long capacity = scale_rt_capacity(cpu);
-	struct sched_group *sdg = sd->groups;
+	struct cfs_rq *cfs_rq = task_cfs_rq(p);
 
-	if (!capacity)
-		capacity = 1;
+	if (!cfs_bandwidth_used())
+		return false;
 
-	cpu_rq(cpu)->cpu_capacity = capacity;
-	trace_sched_cpu_capacity_tp(cpu_rq(cpu));
+	if (cfs_rq->runtime_enabled ||
+	    tg_cfs_bandwidth(cfs_rq->tg)->hierarchical_quota != RUNTIME_INF)
+		return true;
 
-	sdg->sgc->capacity = capacity;
-	sdg->sgc->min_capacity = capacity;
-	sdg->sgc->max_capacity = capacity;
+	return false;
 }
 
-void update_group_capacity(struct sched_domain *sd, int cpu)
+#ifdef CONFIG_NO_HZ_FULL
+/* called from pick_next_task_fair() */
+static void sched_fair_update_stop_tick(struct rq *rq, struct task_struct *p)
 {
-	struct sched_domain *child = sd->child;
-	struct sched_group *group, *sdg = sd->groups;
-	unsigned long capacity, min_capacity, max_capacity;
-	unsigned long interval;
-
-	interval = msecs_to_jiffies(sd->balance_interval);
-	interval = clamp(interval, 1UL, max_load_balance_interval);
-	sdg->sgc->next_update = jiffies + interval;
+	int cpu = cpu_of(rq);
 
-	if (!child) {
-		update_cpu_capacity(sd, cpu);
+	if (!sched_feat(HZ_BW) || !cfs_bandwidth_used())
 		return;
-	}
-
-	capacity = 0;
-	min_capacity = ULONG_MAX;
-	max_capacity = 0;
-
-	if (child->flags & SD_OVERLAP) {
-		/*
-		 * SD_OVERLAP domains cannot assume that child groups
-		 * span the current group.
-		 */
-
-		for_each_cpu(cpu, sched_group_span(sdg)) {
-			unsigned long cpu_cap = capacity_of(cpu);
-
-			capacity += cpu_cap;
-			min_capacity = min(cpu_cap, min_capacity);
-			max_capacity = max(cpu_cap, max_capacity);
-		}
-	} else  {
-		/*
-		 * !SD_OVERLAP domains can assume that child groups
-		 * span the current group.
-		 */
 
-		group = child->groups;
-		do {
-			struct sched_group_capacity *sgc = group->sgc;
+	if (!tick_nohz_full_cpu(cpu))
+		return;
 
-			capacity += sgc->capacity;
-			min_capacity = min(sgc->min_capacity, min_capacity);
-			max_capacity = max(sgc->max_capacity, max_capacity);
-			group = group->next;
-		} while (group != child->groups);
-	}
+	if (rq->nr_running != 1)
+		return;
 
-	sdg->sgc->capacity = capacity;
-	sdg->sgc->min_capacity = min_capacity;
-	sdg->sgc->max_capacity = max_capacity;
+	/*
+	 *  We know there is only one task runnable and we've just picked it. The
+	 *  normal enqueue path will have cleared TICK_DEP_BIT_SCHED if we will
+	 *  be otherwise able to stop the tick. Just need to check if we are using
+	 *  bandwidth control.
+	 */
+	if (cfs_task_bw_constrained(p))
+		tick_nohz_dep_set_cpu(cpu, TICK_DEP_BIT_SCHED);
 }
+#endif
 
-/*
- * Check whether the capacity of the rq has been noticeably reduced by side
- * activity. The imbalance_pct is used for the threshold.
- * Return true is the capacity is reduced
- */
-static inline int
-check_cpu_capacity(struct rq *rq, struct sched_domain *sd)
-{
-	return ((rq->cpu_capacity * sd->imbalance_pct) <
-				(arch_scale_cpu_capacity(cpu_of(rq)) * 100));
-}
+#else /* CONFIG_CFS_BANDWIDTH */
 
-/* Check if the rq has a misfit task */
-static inline bool check_misfit_status(struct rq *rq)
+static inline bool cfs_bandwidth_used(void)
 {
-	return rq->misfit_task_load;
+	return false;
 }
 
-/*
- * Group imbalance indicates (and tries to solve) the problem where balancing
- * groups is inadequate due to ->cpus_ptr constraints.
- *
- * Imagine a situation of two groups of 4 CPUs each and 4 tasks each with a
- * cpumask covering 1 CPU of the first group and 3 CPUs of the second group.
- * Something like:
- *
- *	{ 0 1 2 3 } { 4 5 6 7 }
- *	        *     * * *
- *
- * If we were to balance group-wise we'd place two tasks in the first group and
- * two tasks in the second group. Clearly this is undesired as it will overload
- * cpu 3 and leave one of the CPUs in the second group unused.
- *
- * The current solution to this issue is detecting the skew in the first group
- * by noticing the lower domain failed to reach balance and had difficulty
- * moving tasks due to affinity constraints.
- *
- * When this is so detected; this group becomes a candidate for busiest; see
- * update_sd_pick_busiest(). And calculate_imbalance() and
- * sched_balance_find_src_group() avoid some of the usual balance conditions to allow it
- * to create an effective group imbalance.
- *
- * This is a somewhat tricky proposition since the next run might not find the
- * group imbalance and decide the groups need to be balanced again. A most
- * subtle and fragile situation.
- */
+static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) {}
+static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) { return false; }
+static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
+static inline void sync_throttle(struct task_group *tg, int cpu) {}
+static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
 
-static inline int sg_imbalanced(struct sched_group *group)
+static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
 {
-	return group->sgc->imbalance;
+	return 0;
 }
 
-/*
- * group_has_capacity returns true if the group has spare capacity that could
- * be used by some tasks.
- * We consider that a group has spare capacity if the number of task is
- * smaller than the number of CPUs or if the utilization is lower than the
- * available capacity for CFS tasks.
- * For the latter, we use a threshold to stabilize the state, to take into
- * account the variance of the tasks' load and to return true if the available
- * capacity in meaningful for the load balancer.
- * As an example, an available capacity of 1% can appear but it doesn't make
- * any benefit for the load balance.
- */
-static inline bool
-group_has_capacity(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
+static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
 {
-	if (sgs->sum_nr_running < sgs->group_weight)
-		return true;
-
-	if ((sgs->group_capacity * imbalance_pct) <
-			(sgs->group_runnable * 100))
-		return false;
+	return 0;
+}
 
-	if ((sgs->group_capacity * 100) >
-			(sgs->group_util * imbalance_pct))
-		return true;
+#ifdef CONFIG_FAIR_GROUP_SCHED
+void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b, struct cfs_bandwidth *parent) {}
+static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
+#endif
 
-	return false;
+static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
+{
+	return NULL;
 }
-
-/*
- *  group_is_overloaded returns true if the group has more tasks than it can
- *  handle.
- *  group_is_overloaded is not equals to !group_has_capacity because a group
- *  with the exact right number of tasks, has no more spare capacity but is not
- *  overloaded so both group_has_capacity and group_is_overloaded return
- *  false.
- */
-static inline bool
-group_is_overloaded(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
+static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
+static inline void update_runtime_enabled(struct rq *rq) {}
+static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
+#ifdef CONFIG_CGROUP_SCHED
+bool cfs_task_bw_constrained(struct task_struct *p)
 {
-	if (sgs->sum_nr_running <= sgs->group_weight)
-		return false;
-
-	if ((sgs->group_capacity * 100) <
-			(sgs->group_util * imbalance_pct))
-		return true;
-
-	if ((sgs->group_capacity * imbalance_pct) <
-			(sgs->group_runnable * 100))
-		return true;
-
 	return false;
 }
+#endif
+#endif /* CONFIG_CFS_BANDWIDTH */
 
-static inline enum
-group_type group_classify(unsigned int imbalance_pct,
-			  struct sched_group *group,
-			  struct sg_lb_stats *sgs)
-{
-	if (group_is_overloaded(imbalance_pct, sgs))
-		return group_overloaded;
-
-	if (sg_imbalanced(group))
-		return group_imbalanced;
+#if !defined(CONFIG_CFS_BANDWIDTH) || !defined(CONFIG_NO_HZ_FULL)
+static inline void sched_fair_update_stop_tick(struct rq *rq, struct task_struct *p) {}
+#endif
 
-	if (sgs->group_asym_packing)
-		return group_asym_packing;
+/**************************************************
+ * CFS operations on tasks:
+ */
 
-	if (sgs->group_smt_balance)
-		return group_smt_balance;
+#ifdef CONFIG_SCHED_HRTICK
+static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
+{
+	struct sched_entity *se = &p->se;
 
-	if (sgs->group_misfit_task_load)
-		return group_misfit_task;
+	SCHED_WARN_ON(task_rq(p) != rq);
 
-	if (!group_has_capacity(imbalance_pct, sgs))
-		return group_fully_busy;
+	if (rq->cfs.h_nr_running > 1) {
+		u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
+		u64 slice = se->slice;
+		s64 delta = slice - ran;
 
-	return group_has_spare;
+		if (delta < 0) {
+			if (task_current(rq, p))
+				resched_curr(rq);
+			return;
+		}
+		hrtick_start(rq, delta);
+	}
 }
 
-/**
- * sched_use_asym_prio - Check whether asym_packing priority must be used
- * @sd:		The scheduling domain of the load balancing
- * @cpu:	A CPU
- *
- * Always use CPU priority when balancing load between SMT siblings. When
- * balancing load between cores, it is not sufficient that @cpu is idle. Only
- * use CPU priority if the whole core is idle.
- *
- * Returns: True if the priority of @cpu must be followed. False otherwise.
+/*
+ * called from enqueue/dequeue and updates the hrtick when the
+ * current task is from our class and nr_running is low enough
+ * to matter.
  */
-static bool sched_use_asym_prio(struct sched_domain *sd, int cpu)
+static void hrtick_update(struct rq *rq)
 {
-	if (!(sd->flags & SD_ASYM_PACKING))
-		return false;
+	struct task_struct *curr = rq->curr;
 
-	if (!sched_smt_active())
-		return true;
+	if (!hrtick_enabled_fair(rq) || curr->sched_class != &fair_sched_class)
+		return;
 
-	return sd->flags & SD_SHARE_CPUCAPACITY || is_core_idle(cpu);
+	hrtick_start_fair(rq, curr);
 }
-
-static inline bool sched_asym(struct sched_domain *sd, int dst_cpu, int src_cpu)
+#else /* !CONFIG_SCHED_HRTICK */
+static inline void
+hrtick_start_fair(struct rq *rq, struct task_struct *p)
 {
-	/*
-	 * First check if @dst_cpu can do asym_packing load balance. Only do it
-	 * if it has higher priority than @src_cpu.
-	 */
-	return sched_use_asym_prio(sd, dst_cpu) &&
-		sched_asym_prefer(dst_cpu, src_cpu);
 }
 
-/**
- * sched_group_asym - Check if the destination CPU can do asym_packing balance
- * @env:	The load balancing environment
- * @sgs:	Load-balancing statistics of the candidate busiest group
- * @group:	The candidate busiest group
- *
- * @env::dst_cpu can do asym_packing if it has higher priority than the
- * preferred CPU of @group.
- *
- * Return: true if @env::dst_cpu can do with asym_packing load balance. False
- * otherwise.
- */
-static inline bool
-sched_group_asym(struct lb_env *env, struct sg_lb_stats *sgs, struct sched_group *group)
+static inline void hrtick_update(struct rq *rq)
 {
-	/*
-	 * CPU priorities do not make sense for SMT cores with more than one
-	 * busy sibling.
-	 */
-	if ((group->flags & SD_SHARE_CPUCAPACITY) &&
-	    (sgs->group_weight - sgs->idle_cpus != 1))
-		return false;
-
-	return sched_asym(env->sd, env->dst_cpu, group->asym_prefer_cpu);
 }
+#endif
 
-/* One group has more than one SMT CPU while the other group does not */
-static inline bool smt_vs_nonsmt_groups(struct sched_group *sg1,
-				    struct sched_group *sg2)
+/* Runqueue only has SCHED_IDLE tasks enqueued */
+static int sched_idle_rq(struct rq *rq)
 {
-	if (!sg1 || !sg2)
-		return false;
-
-	return (sg1->flags & SD_SHARE_CPUCAPACITY) !=
-		(sg2->flags & SD_SHARE_CPUCAPACITY);
+	return unlikely(rq->nr_running == rq->cfs.idle_h_nr_running &&
+			rq->nr_running);
 }
 
-static inline bool smt_balance(struct lb_env *env, struct sg_lb_stats *sgs,
-			       struct sched_group *group)
+#ifdef CONFIG_SMP
+int sched_idle_cpu(int cpu)
 {
-	if (!env->idle)
-		return false;
-
-	/*
-	 * For SMT source group, it is better to move a task
-	 * to a CPU that doesn't have multiple tasks sharing its CPU capacity.
-	 * Note that if a group has a single SMT, SD_SHARE_CPUCAPACITY
-	 * will not be on.
-	 */
-	if (group->flags & SD_SHARE_CPUCAPACITY &&
-	    sgs->sum_h_nr_running > 1)
-		return true;
-
-	return false;
+	return sched_idle_rq(cpu_rq(cpu));
 }
+#endif
 
-static inline long sibling_imbalance(struct lb_env *env,
-				    struct sd_lb_stats *sds,
-				    struct sg_lb_stats *busiest,
-				    struct sg_lb_stats *local)
+/*
+ * The enqueue_task method is called before nr_running is
+ * increased. Here we update the fair scheduling stats and
+ * then put the task into the rbtree:
+ */
+static void
+enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 {
-	int ncores_busiest, ncores_local;
-	long imbalance;
-
-	if (!env->idle || !busiest->sum_nr_running)
-		return 0;
-
-	ncores_busiest = sds->busiest->cores;
-	ncores_local = sds->local->cores;
-
-	if (ncores_busiest == ncores_local) {
-		imbalance = busiest->sum_nr_running;
-		lsub_positive(&imbalance, local->sum_nr_running);
-		return imbalance;
-	}
-
-	/* Balance such that nr_running/ncores ratio are same on both groups */
-	imbalance = ncores_local * busiest->sum_nr_running;
-	lsub_positive(&imbalance, ncores_busiest * local->sum_nr_running);
-	/* Normalize imbalance and do rounding on normalization */
-	imbalance = 2 * imbalance + ncores_local + ncores_busiest;
-	imbalance /= ncores_local + ncores_busiest;
-
-	/* Take advantage of resource in an empty sched group */
-	if (imbalance <= 1 && local->sum_nr_running == 0 &&
-	    busiest->sum_nr_running > 1)
-		imbalance = 2;
-
-	return imbalance;
-}
+	struct cfs_rq *cfs_rq;
+	struct sched_entity *se = &p->se;
+	int idle_h_nr_running = task_has_idle_policy(p);
+	int task_new = !(flags & ENQUEUE_WAKEUP);
 
-static inline bool
-sched_reduced_capacity(struct rq *rq, struct sched_domain *sd)
-{
 	/*
-	 * When there is more than 1 task, the group_overloaded case already
-	 * takes care of cpu with reduced capacity
+	 * The code below (indirectly) updates schedutil which looks at
+	 * the cfs_rq utilization to select a frequency.
+	 * Let's add the task's estimated utilization to the cfs_rq's
+	 * estimated utilization, before we update schedutil.
 	 */
-	if (rq->cfs.h_nr_running != 1)
-		return false;
-
-	return check_cpu_capacity(rq, sd);
-}
-
-/**
- * update_sg_lb_stats - Update sched_group's statistics for load balancing.
- * @env: The load balancing environment.
- * @sds: Load-balancing data with statistics of the local group.
- * @group: sched_group whose statistics are to be updated.
- * @sgs: variable to hold the statistics for this group.
- * @sg_overloaded: sched_group is overloaded
- * @sg_overutilized: sched_group is overutilized
- */
-static inline void update_sg_lb_stats(struct lb_env *env,
-				      struct sd_lb_stats *sds,
-				      struct sched_group *group,
-				      struct sg_lb_stats *sgs,
-				      bool *sg_overloaded,
-				      bool *sg_overutilized)
-{
-	int i, nr_running, local_group;
-
-	memset(sgs, 0, sizeof(*sgs));
-
-	local_group = group == sds->local;
-
-	for_each_cpu_and(i, sched_group_span(group), env->cpus) {
-		struct rq *rq = cpu_rq(i);
-		unsigned long load = cpu_load(rq);
-
-		sgs->group_load += load;
-		sgs->group_util += cpu_util_cfs(i);
-		sgs->group_runnable += cpu_runnable(rq);
-		sgs->sum_h_nr_running += rq->cfs.h_nr_running;
+	util_est_enqueue(&rq->cfs, p);
 
-		nr_running = rq->nr_running;
-		sgs->sum_nr_running += nr_running;
+	/*
+	 * If in_iowait is set, the code below may not trigger any cpufreq
+	 * utilization updates, so do it here explicitly with the IOWAIT flag
+	 * passed.
+	 */
+	if (p->in_iowait)
+		cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT);
 
-		if (nr_running > 1)
-			*sg_overloaded = 1;
+	for_each_sched_entity(se) {
+		if (se->on_rq)
+			break;
+		cfs_rq = cfs_rq_of(se);
+		enqueue_entity(cfs_rq, se, flags);
 
-		if (cpu_overutilized(i))
-			*sg_overutilized = 1;
+		cfs_rq->h_nr_running++;
+		cfs_rq->idle_h_nr_running += idle_h_nr_running;
 
-#ifdef CONFIG_NUMA_BALANCING
-		sgs->nr_numa_running += rq->nr_numa_running;
-		sgs->nr_preferred_running += rq->nr_preferred_running;
-#endif
-		/*
-		 * No need to call idle_cpu() if nr_running is not 0
-		 */
-		if (!nr_running && idle_cpu(i)) {
-			sgs->idle_cpus++;
-			/* Idle cpu can't have misfit task */
-			continue;
-		}
+		if (cfs_rq_is_idle(cfs_rq))
+			idle_h_nr_running = 1;
 
-		if (local_group)
-			continue;
+		/* end evaluation on encountering a throttled cfs_rq */
+		if (cfs_rq_throttled(cfs_rq))
+			goto enqueue_throttle;
 
-		if (env->sd->flags & SD_ASYM_CPUCAPACITY) {
-			/* Check for a misfit task on the cpu */
-			if (sgs->group_misfit_task_load < rq->misfit_task_load) {
-				sgs->group_misfit_task_load = rq->misfit_task_load;
-				*sg_overloaded = 1;
-			}
-		} else if (env->idle && sched_reduced_capacity(rq, env->sd)) {
-			/* Check for a task running on a CPU with reduced capacity */
-			if (sgs->group_misfit_task_load < load)
-				sgs->group_misfit_task_load = load;
-		}
+		flags = ENQUEUE_WAKEUP;
 	}
 
-	sgs->group_capacity = group->sgc->capacity;
-
-	sgs->group_weight = group->group_weight;
-
-	/* Check if dst CPU is idle and preferred to this group */
-	if (!local_group && env->idle && sgs->sum_h_nr_running &&
-	    sched_group_asym(env, sgs, group))
-		sgs->group_asym_packing = 1;
+	for_each_sched_entity(se) {
+		cfs_rq = cfs_rq_of(se);
 
-	/* Check for loaded SMT group to be balanced to dst CPU */
-	if (!local_group && smt_balance(env, sgs, group))
-		sgs->group_smt_balance = 1;
+		update_load_avg(cfs_rq, se, UPDATE_TG);
+		se_update_runnable(se);
+		update_cfs_group(se);
 
-	sgs->group_type = group_classify(env->sd->imbalance_pct, group, sgs);
+		cfs_rq->h_nr_running++;
+		cfs_rq->idle_h_nr_running += idle_h_nr_running;
 
-	/* Computing avg_load makes sense only when group is overloaded */
-	if (sgs->group_type == group_overloaded)
-		sgs->avg_load = (sgs->group_load * SCHED_CAPACITY_SCALE) /
-				sgs->group_capacity;
-}
+		if (cfs_rq_is_idle(cfs_rq))
+			idle_h_nr_running = 1;
 
-/**
- * update_sd_pick_busiest - return 1 on busiest group
- * @env: The load balancing environment.
- * @sds: sched_domain statistics
- * @sg: sched_group candidate to be checked for being the busiest
- * @sgs: sched_group statistics
- *
- * Determine if @sg is a busier group than the previously selected
- * busiest group.
- *
- * Return: %true if @sg is a busier group than the previously selected
- * busiest group. %false otherwise.
- */
-static bool update_sd_pick_busiest(struct lb_env *env,
-				   struct sd_lb_stats *sds,
-				   struct sched_group *sg,
-				   struct sg_lb_stats *sgs)
-{
-	struct sg_lb_stats *busiest = &sds->busiest_stat;
+		/* end evaluation on encountering a throttled cfs_rq */
+		if (cfs_rq_throttled(cfs_rq))
+			goto enqueue_throttle;
+	}
 
-	/* Make sure that there is at least one task to pull */
-	if (!sgs->sum_h_nr_running)
-		return false;
+	/* At this point se is NULL and we are at root level*/
+	add_nr_running(rq, 1);
 
 	/*
-	 * Don't try to pull misfit tasks we can't help.
-	 * We can use max_capacity here as reduction in capacity on some
-	 * CPUs in the group should either be possible to resolve
-	 * internally or be covered by avg_load imbalance (eventually).
+	 * Since new tasks are assigned an initial util_avg equal to
+	 * half of the spare capacity of their CPU, tiny tasks have the
+	 * ability to cross the overutilized threshold, which will
+	 * result in the load balancer ruining all the task placement
+	 * done by EAS. As a way to mitigate that effect, do not account
+	 * for the first enqueue operation of new tasks during the
+	 * overutilized flag detection.
+	 *
+	 * A better way of solving this problem would be to wait for
+	 * the PELT signals of tasks to converge before taking them
+	 * into account, but that is not straightforward to implement,
+	 * and the following generally works well enough in practice.
 	 */
-	if ((env->sd->flags & SD_ASYM_CPUCAPACITY) &&
-	    (sgs->group_type == group_misfit_task) &&
-	    (!capacity_greater(capacity_of(env->dst_cpu), sg->sgc->max_capacity) ||
-	     sds->local_stat.group_type != group_has_spare))
-		return false;
-
-	if (sgs->group_type > busiest->group_type)
-		return true;
-
-	if (sgs->group_type < busiest->group_type)
-		return false;
+	if (!task_new)
+		check_update_overutilized_status(rq);
 
-	/*
-	 * The candidate and the current busiest group are the same type of
-	 * group. Let check which one is the busiest according to the type.
-	 */
+enqueue_throttle:
+	assert_list_leaf_cfs_rq(rq);
 
-	switch (sgs->group_type) {
-	case group_overloaded:
-		/* Select the overloaded group with highest avg_load. */
-		return sgs->avg_load > busiest->avg_load;
+	hrtick_update(rq);
+}
 
-	case group_imbalanced:
-		/*
-		 * Select the 1st imbalanced group as we don't have any way to
-		 * choose one more than another.
-		 */
-		return false;
+static void set_next_buddy(struct sched_entity *se);
 
-	case group_asym_packing:
-		/* Prefer to move from lowest priority CPU's work */
-		return sched_asym_prefer(sds->busiest->asym_prefer_cpu, sg->asym_prefer_cpu);
+/*
+ * The dequeue_task method is called before nr_running is
+ * decreased. We remove the task from the rbtree and
+ * update the fair scheduling stats:
+ */
+static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
+{
+	struct cfs_rq *cfs_rq;
+	struct sched_entity *se = &p->se;
+	int task_sleep = flags & DEQUEUE_SLEEP;
+	int idle_h_nr_running = task_has_idle_policy(p);
+	bool was_sched_idle = sched_idle_rq(rq);
 
-	case group_misfit_task:
-		/*
-		 * If we have more than one misfit sg go with the biggest
-		 * misfit.
-		 */
-		return sgs->group_misfit_task_load > busiest->group_misfit_task_load;
+	util_est_dequeue(&rq->cfs, p);
 
-	case group_smt_balance:
-		/*
-		 * Check if we have spare CPUs on either SMT group to
-		 * choose has spare or fully busy handling.
-		 */
-		if (sgs->idle_cpus != 0 || busiest->idle_cpus != 0)
-			goto has_spare;
+	for_each_sched_entity(se) {
+		cfs_rq = cfs_rq_of(se);
+		dequeue_entity(cfs_rq, se, flags);
 
-		fallthrough;
+		cfs_rq->h_nr_running--;
+		cfs_rq->idle_h_nr_running -= idle_h_nr_running;
 
-	case group_fully_busy:
-		/*
-		 * Select the fully busy group with highest avg_load. In
-		 * theory, there is no need to pull task from such kind of
-		 * group because tasks have all compute capacity that they need
-		 * but we can still improve the overall throughput by reducing
-		 * contention when accessing shared HW resources.
-		 *
-		 * XXX for now avg_load is not computed and always 0 so we
-		 * select the 1st one, except if @sg is composed of SMT
-		 * siblings.
-		 */
+		if (cfs_rq_is_idle(cfs_rq))
+			idle_h_nr_running = 1;
 
-		if (sgs->avg_load < busiest->avg_load)
-			return false;
+		/* end evaluation on encountering a throttled cfs_rq */
+		if (cfs_rq_throttled(cfs_rq))
+			goto dequeue_throttle;
 
-		if (sgs->avg_load == busiest->avg_load) {
+		/* Don't dequeue parent if it has other entities besides us */
+		if (cfs_rq->load.weight) {
+			/* Avoid re-evaluating load for this entity: */
+			se = parent_entity(se);
 			/*
-			 * SMT sched groups need more help than non-SMT groups.
-			 * If @sg happens to also be SMT, either choice is good.
+			 * Bias pick_next to pick a task from this cfs_rq, as
+			 * p is sleeping when it is within its sched_slice.
 			 */
-			if (sds->busiest->flags & SD_SHARE_CPUCAPACITY)
-				return false;
+			if (task_sleep && se && !throttled_hierarchy(cfs_rq))
+				set_next_buddy(se);
+			break;
 		}
+		flags |= DEQUEUE_SLEEP;
+	}
 
-		break;
+	for_each_sched_entity(se) {
+		cfs_rq = cfs_rq_of(se);
 
-	case group_has_spare:
-		/*
-		 * Do not pick sg with SMT CPUs over sg with pure CPUs,
-		 * as we do not want to pull task off SMT core with one task
-		 * and make the core idle.
-		 */
-		if (smt_vs_nonsmt_groups(sds->busiest, sg)) {
-			if (sg->flags & SD_SHARE_CPUCAPACITY && sgs->sum_h_nr_running <= 1)
-				return false;
-			else
-				return true;
-		}
-has_spare:
+		update_load_avg(cfs_rq, se, UPDATE_TG);
+		se_update_runnable(se);
+		update_cfs_group(se);
 
-		/*
-		 * Select not overloaded group with lowest number of idle CPUs
-		 * and highest number of running tasks. We could also compare
-		 * the spare capacity which is more stable but it can end up
-		 * that the group has less spare capacity but finally more idle
-		 * CPUs which means less opportunity to pull tasks.
-		 */
-		if (sgs->idle_cpus > busiest->idle_cpus)
-			return false;
-		else if ((sgs->idle_cpus == busiest->idle_cpus) &&
-			 (sgs->sum_nr_running <= busiest->sum_nr_running))
-			return false;
+		cfs_rq->h_nr_running--;
+		cfs_rq->idle_h_nr_running -= idle_h_nr_running;
+
+		if (cfs_rq_is_idle(cfs_rq))
+			idle_h_nr_running = 1;
+
+		/* end evaluation on encountering a throttled cfs_rq */
+		if (cfs_rq_throttled(cfs_rq))
+			goto dequeue_throttle;
 
-		break;
 	}
 
-	/*
-	 * Candidate sg has no more than one task per CPU and has higher
-	 * per-CPU capacity. Migrating tasks to less capable CPUs may harm
-	 * throughput. Maximize throughput, power/energy consequences are not
-	 * considered.
-	 */
-	if ((env->sd->flags & SD_ASYM_CPUCAPACITY) &&
-	    (sgs->group_type <= group_fully_busy) &&
-	    (capacity_greater(sg->sgc->min_capacity, capacity_of(env->dst_cpu))))
-		return false;
+	/* At this point se is NULL and we are at root level*/
+	sub_nr_running(rq, 1);
 
-	return true;
-}
+	/* balance early to pull high priority tasks */
+	if (unlikely(!was_sched_idle && sched_idle_rq(rq)))
+		rq->next_balance = jiffies;
 
-#ifdef CONFIG_NUMA_BALANCING
-static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs)
-{
-	if (sgs->sum_h_nr_running > sgs->nr_numa_running)
-		return regular;
-	if (sgs->sum_h_nr_running > sgs->nr_preferred_running)
-		return remote;
-	return all;
+dequeue_throttle:
+	util_est_update(&rq->cfs, p, task_sleep);
+	hrtick_update(rq);
 }
 
-static inline enum fbq_type fbq_classify_rq(struct rq *rq)
+#ifdef CONFIG_SMP
+
+DEFINE_PER_CPU(cpumask_var_t, select_rq_mask);
+
+static inline unsigned long cfs_rq_runnable_avg(struct cfs_rq *cfs_rq)
 {
-	if (rq->nr_running > rq->nr_numa_running)
-		return regular;
-	if (rq->nr_running > rq->nr_preferred_running)
-		return remote;
-	return all;
+	return cfs_rq->avg.runnable_avg;
 }
-#else
-static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs)
+
+unsigned long cpu_runnable(struct rq *rq)
 {
-	return all;
+	return cfs_rq_runnable_avg(&rq->cfs);
 }
 
-static inline enum fbq_type fbq_classify_rq(struct rq *rq)
+unsigned long cpu_runnable_without(struct rq *rq, struct task_struct *p)
 {
-	return regular;
-}
-#endif /* CONFIG_NUMA_BALANCING */
+	struct cfs_rq *cfs_rq;
+	unsigned int runnable;
+
+	/* Task has no contribution or is new */
+	if (cpu_of(rq) != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
+		return cpu_runnable(rq);
 
+	cfs_rq = &rq->cfs;
+	runnable = READ_ONCE(cfs_rq->avg.runnable_avg);
 
-struct sg_lb_stats;
+	/* Discount task's runnable from CPU's runnable */
+	lsub_positive(&runnable, p->se.avg.runnable_avg);
 
-/*
- * task_running_on_cpu - return 1 if @p is running on @cpu.
- */
+	return runnable;
+}
 
-static unsigned int task_running_on_cpu(int cpu, struct task_struct *p)
+static void record_wakee(struct task_struct *p)
 {
-	/* Task has no contribution or is new */
-	if (cpu != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
-		return 0;
-
-	if (task_on_rq_queued(p))
-		return 1;
+	/*
+	 * Only decay a single time; tasks that have less then 1 wakeup per
+	 * jiffy will not have built up many flips.
+	 */
+	if (time_after(jiffies, current->wakee_flip_decay_ts + HZ)) {
+		current->wakee_flips >>= 1;
+		current->wakee_flip_decay_ts = jiffies;
+	}
 
-	return 0;
+	if (current->last_wakee != p) {
+		current->last_wakee = p;
+		current->wakee_flips++;
+	}
 }
 
-/**
- * idle_cpu_without - would a given CPU be idle without p ?
- * @cpu: the processor on which idleness is tested.
- * @p: task which should be ignored.
+/*
+ * Detect M:N waker/wakee relationships via a switching-frequency heuristic.
+ *
+ * A waker of many should wake a different task than the one last awakened
+ * at a frequency roughly N times higher than one of its wakees.
  *
- * Return: 1 if the CPU would be idle. 0 otherwise.
+ * In order to determine whether we should let the load spread vs consolidating
+ * to shared cache, we look for a minimum 'flip' frequency of llc_size in one
+ * partner, and a factor of lls_size higher frequency in the other.
+ *
+ * With both conditions met, we can be relatively sure that the relationship is
+ * non-monogamous, with partner count exceeding socket size.
+ *
+ * Waker/wakee being client/server, worker/dispatcher, interrupt source or
+ * whatever is irrelevant, spread criteria is apparent partner count exceeds
+ * socket size.
  */
-static int idle_cpu_without(int cpu, struct task_struct *p)
+static int wake_wide(struct task_struct *p)
 {
-	struct rq *rq = cpu_rq(cpu);
+	unsigned int master = current->wakee_flips;
+	unsigned int slave = p->wakee_flips;
+	int factor = __this_cpu_read(sd_llc_size);
 
-	if (rq->curr != rq->idle && rq->curr != p)
+	if (master < slave)
+		swap(master, slave);
+	if (slave < factor || master < slave * factor)
 		return 0;
+	return 1;
+}
 
+/*
+ * The purpose of wake_affine() is to quickly determine on which CPU we can run
+ * soonest. For the purpose of speed we only consider the waking and previous
+ * CPU.
+ *
+ * wake_affine_idle() - only considers 'now', it check if the waking CPU is
+ *			cache-affine and is (or	will be) idle.
+ *
+ * wake_affine_weight() - considers the weight to reflect the average
+ *			  scheduling latency of the CPUs. This seems to work
+ *			  for the overloaded case.
+ */
+static int
+wake_affine_idle(int this_cpu, int prev_cpu, int sync)
+{
 	/*
-	 * rq->nr_running can't be used but an updated version without the
-	 * impact of p on cpu must be used instead. The updated nr_running
-	 * be computed and tested before calling idle_cpu_without().
+	 * If this_cpu is idle, it implies the wakeup is from interrupt
+	 * context. Only allow the move if cache is shared. Otherwise an
+	 * interrupt intensive workload could force all tasks onto one
+	 * node depending on the IO topology or IRQ affinity settings.
+	 *
+	 * If the prev_cpu is idle and cache affine then avoid a migration.
+	 * There is no guarantee that the cache hot data from an interrupt
+	 * is more important than cache hot data on the prev_cpu and from
+	 * a cpufreq perspective, it's better to have higher utilisation
+	 * on one CPU.
 	 */
+	if (available_idle_cpu(this_cpu) && cpus_share_cache(this_cpu, prev_cpu))
+		return available_idle_cpu(prev_cpu) ? prev_cpu : this_cpu;
+
+	if (sync && cpu_rq(this_cpu)->nr_running == 1)
+		return this_cpu;
 
-	if (rq->ttwu_pending)
-		return 0;
+	if (available_idle_cpu(prev_cpu))
+		return prev_cpu;
 
-	return 1;
+	return nr_cpumask_bits;
 }
 
-/*
- * update_sg_wakeup_stats - Update sched_group's statistics for wakeup.
- * @sd: The sched_domain level to look for idlest group.
- * @group: sched_group whose statistics are to be updated.
- * @sgs: variable to hold the statistics for this group.
- * @p: The task for which we look for the idlest group/CPU.
- */
-static inline void update_sg_wakeup_stats(struct sched_domain *sd,
-					  struct sched_group *group,
-					  struct sg_lb_stats *sgs,
-					  struct task_struct *p)
+static int
+wake_affine_weight(struct sched_domain *sd, struct task_struct *p,
+		   int this_cpu, int prev_cpu, int sync)
 {
-	int i, nr_running;
-
-	memset(sgs, 0, sizeof(*sgs));
-
-	/* Assume that task can't fit any CPU of the group */
-	if (sd->flags & SD_ASYM_CPUCAPACITY)
-		sgs->group_misfit_task_load = 1;
-
-	for_each_cpu(i, sched_group_span(group)) {
-		struct rq *rq = cpu_rq(i);
-		unsigned int local;
-
-		sgs->group_load += cpu_load_without(rq, p);
-		sgs->group_util += cpu_util_without(i, p);
-		sgs->group_runnable += cpu_runnable_without(rq, p);
-		local = task_running_on_cpu(i, p);
-		sgs->sum_h_nr_running += rq->cfs.h_nr_running - local;
+	s64 this_eff_load, prev_eff_load;
+	unsigned long task_load;
 
-		nr_running = rq->nr_running - local;
-		sgs->sum_nr_running += nr_running;
+	this_eff_load = cpu_load(cpu_rq(this_cpu));
 
-		/*
-		 * No need to call idle_cpu_without() if nr_running is not 0
-		 */
-		if (!nr_running && idle_cpu_without(i, p))
-			sgs->idle_cpus++;
+	if (sync) {
+		unsigned long current_load = task_h_load(current);
 
-		/* Check if task fits in the CPU */
-		if (sd->flags & SD_ASYM_CPUCAPACITY &&
-		    sgs->group_misfit_task_load &&
-		    task_fits_cpu(p, i))
-			sgs->group_misfit_task_load = 0;
+		if (current_load > this_eff_load)
+			return this_cpu;
 
+		this_eff_load -= current_load;
 	}
 
-	sgs->group_capacity = group->sgc->capacity;
+	task_load = task_h_load(p);
 
-	sgs->group_weight = group->group_weight;
+	this_eff_load += task_load;
+	if (sched_feat(WA_BIAS))
+		this_eff_load *= 100;
+	this_eff_load *= capacity_of(prev_cpu);
 
-	sgs->group_type = group_classify(sd->imbalance_pct, group, sgs);
+	prev_eff_load = cpu_load(cpu_rq(prev_cpu));
+	prev_eff_load -= task_load;
+	if (sched_feat(WA_BIAS))
+		prev_eff_load *= 100 + (sd->imbalance_pct - 100) / 2;
+	prev_eff_load *= capacity_of(this_cpu);
 
 	/*
-	 * Computing avg_load makes sense only when group is fully busy or
-	 * overloaded
+	 * If sync, adjust the weight of prev_eff_load such that if
+	 * prev_eff == this_eff that select_idle_sibling() will consider
+	 * stacking the wakee on top of the waker if no other CPU is
+	 * idle.
 	 */
-	if (sgs->group_type == group_fully_busy ||
-		sgs->group_type == group_overloaded)
-		sgs->avg_load = (sgs->group_load * SCHED_CAPACITY_SCALE) /
-				sgs->group_capacity;
+	if (sync)
+		prev_eff_load += 1;
+
+	return this_eff_load < prev_eff_load ? this_cpu : nr_cpumask_bits;
 }
 
-static bool update_pick_idlest(struct sched_group *idlest,
-			       struct sg_lb_stats *idlest_sgs,
-			       struct sched_group *group,
-			       struct sg_lb_stats *sgs)
+static int wake_affine(struct sched_domain *sd, struct task_struct *p,
+		       int this_cpu, int prev_cpu, int sync)
 {
-	if (sgs->group_type < idlest_sgs->group_type)
-		return true;
-
-	if (sgs->group_type > idlest_sgs->group_type)
-		return false;
-
-	/*
-	 * The candidate and the current idlest group are the same type of
-	 * group. Let check which one is the idlest according to the type.
-	 */
-
-	switch (sgs->group_type) {
-	case group_overloaded:
-	case group_fully_busy:
-		/* Select the group with lowest avg_load. */
-		if (idlest_sgs->avg_load <= sgs->avg_load)
-			return false;
-		break;
-
-	case group_imbalanced:
-	case group_asym_packing:
-	case group_smt_balance:
-		/* Those types are not used in the slow wakeup path */
-		return false;
-
-	case group_misfit_task:
-		/* Select group with the highest max capacity */
-		if (idlest->sgc->max_capacity >= group->sgc->max_capacity)
-			return false;
-		break;
+	int target = nr_cpumask_bits;
 
-	case group_has_spare:
-		/* Select group with most idle CPUs */
-		if (idlest_sgs->idle_cpus > sgs->idle_cpus)
-			return false;
+	if (sched_feat(WA_IDLE))
+		target = wake_affine_idle(this_cpu, prev_cpu, sync);
 
-		/* Select group with lowest group_util */
-		if (idlest_sgs->idle_cpus == sgs->idle_cpus &&
-			idlest_sgs->group_util <= sgs->group_util)
-			return false;
+	if (sched_feat(WA_WEIGHT) && target == nr_cpumask_bits)
+		target = wake_affine_weight(sd, p, this_cpu, prev_cpu, sync);
 
-		break;
-	}
+	schedstat_inc(p->stats.nr_wakeups_affine_attempts);
+	if (target != this_cpu)
+		return prev_cpu;
 
-	return true;
+	schedstat_inc(sd->ttwu_move_affine);
+	schedstat_inc(p->stats.nr_wakeups_affine);
+	return target;
 }
 
 /*
- * sched_balance_find_dst_group() finds and returns the least busy CPU group within the
- * domain.
- *
- * Assumes p is allowed on at least one CPU in sd.
+ * sched_balance_find_dst_group_cpu - find the idlest CPU among the CPUs in the group.
  */
-static struct sched_group *
-sched_balance_find_dst_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
-{
-	struct sched_group *idlest = NULL, *local = NULL, *group = sd->groups;
-	struct sg_lb_stats local_sgs, tmp_sgs;
-	struct sg_lb_stats *sgs;
-	unsigned long imbalance;
-	struct sg_lb_stats idlest_sgs = {
-			.avg_load = UINT_MAX,
-			.group_type = group_overloaded,
-	};
+static int
+sched_balance_find_dst_group_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
+{
+	unsigned long load, min_load = ULONG_MAX;
+	unsigned int min_exit_latency = UINT_MAX;
+	u64 latest_idle_timestamp = 0;
+	int least_loaded_cpu = this_cpu;
+	int shallowest_idle_cpu = -1;
+	int i;
 
-	do {
-		int local_group;
+	/* Check if we have any choice: */
+	if (group->group_weight == 1)
+		return cpumask_first(sched_group_span(group));
 
-		/* Skip over this group if it has no CPUs allowed */
-		if (!cpumask_intersects(sched_group_span(group),
-					p->cpus_ptr))
-			continue;
+	/* Traverse only the allowed CPUs */
+	for_each_cpu_and(i, sched_group_span(group), p->cpus_ptr) {
+		struct rq *rq = cpu_rq(i);
 
-		/* Skip over this group if no cookie matched */
-		if (!sched_group_cookie_match(cpu_rq(this_cpu), p, group))
+		if (!sched_core_cookie_match(rq, p))
 			continue;
 
-		local_group = cpumask_test_cpu(this_cpu,
-					       sched_group_span(group));
-
-		if (local_group) {
-			sgs = &local_sgs;
-			local = group;
-		} else {
-			sgs = &tmp_sgs;
-		}
-
-		update_sg_wakeup_stats(sd, group, sgs, p);
-
-		if (!local_group && update_pick_idlest(idlest, &idlest_sgs, group, sgs)) {
-			idlest = group;
-			idlest_sgs = *sgs;
-		}
-
-	} while (group = group->next, group != sd->groups);
-
-
-	/* There is no idlest group to push tasks to */
-	if (!idlest)
-		return NULL;
-
-	/* The local group has been skipped because of CPU affinity */
-	if (!local)
-		return idlest;
-
-	/*
-	 * If the local group is idler than the selected idlest group
-	 * don't try and push the task.
-	 */
-	if (local_sgs.group_type < idlest_sgs.group_type)
-		return NULL;
-
-	/*
-	 * If the local group is busier than the selected idlest group
-	 * try and push the task.
-	 */
-	if (local_sgs.group_type > idlest_sgs.group_type)
-		return idlest;
-
-	switch (local_sgs.group_type) {
-	case group_overloaded:
-	case group_fully_busy:
-
-		/* Calculate allowed imbalance based on load */
-		imbalance = scale_load_down(NICE_0_LOAD) *
-				(sd->imbalance_pct-100) / 100;
-
-		/*
-		 * When comparing groups across NUMA domains, it's possible for
-		 * the local domain to be very lightly loaded relative to the
-		 * remote domains but "imbalance" skews the comparison making
-		 * remote CPUs look much more favourable. When considering
-		 * cross-domain, add imbalance to the load on the remote node
-		 * and consider staying local.
-		 */
-
-		if ((sd->flags & SD_NUMA) &&
-		    ((idlest_sgs.avg_load + imbalance) >= local_sgs.avg_load))
-			return NULL;
-
-		/*
-		 * If the local group is less loaded than the selected
-		 * idlest group don't try and push any tasks.
-		 */
-		if (idlest_sgs.avg_load >= (local_sgs.avg_load + imbalance))
-			return NULL;
-
-		if (100 * local_sgs.avg_load <= sd->imbalance_pct * idlest_sgs.avg_load)
-			return NULL;
-		break;
-
-	case group_imbalanced:
-	case group_asym_packing:
-	case group_smt_balance:
-		/* Those type are not used in the slow wakeup path */
-		return NULL;
-
-	case group_misfit_task:
-		/* Select group with the highest max capacity */
-		if (local->sgc->max_capacity >= idlest->sgc->max_capacity)
-			return NULL;
-		break;
-
-	case group_has_spare:
-#ifdef CONFIG_NUMA
-		if (sd->flags & SD_NUMA) {
-			int imb_numa_nr = sd->imb_numa_nr;
-#ifdef CONFIG_NUMA_BALANCING
-			int idlest_cpu;
-			/*
-			 * If there is spare capacity at NUMA, try to select
-			 * the preferred node
-			 */
-			if (cpu_to_node(this_cpu) == p->numa_preferred_nid)
-				return NULL;
-
-			idlest_cpu = cpumask_first(sched_group_span(idlest));
-			if (cpu_to_node(idlest_cpu) == p->numa_preferred_nid)
-				return idlest;
-#endif /* CONFIG_NUMA_BALANCING */
-			/*
-			 * Otherwise, keep the task close to the wakeup source
-			 * and improve locality if the number of running tasks
-			 * would remain below threshold where an imbalance is
-			 * allowed while accounting for the possibility the
-			 * task is pinned to a subset of CPUs. If there is a
-			 * real need of migration, periodic load balance will
-			 * take care of it.
-			 */
-			if (p->nr_cpus_allowed != NR_CPUS) {
-				struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
+		if (sched_idle_cpu(i))
+			return i;
 
-				cpumask_and(cpus, sched_group_span(local), p->cpus_ptr);
-				imb_numa_nr = min(cpumask_weight(cpus), sd->imb_numa_nr);
+		if (available_idle_cpu(i)) {
+			struct cpuidle_state *idle = idle_get_state(rq);
+			if (idle && idle->exit_latency < min_exit_latency) {
+				/*
+				 * We give priority to a CPU whose idle state
+				 * has the smallest exit latency irrespective
+				 * of any idle timestamp.
+				 */
+				min_exit_latency = idle->exit_latency;
+				latest_idle_timestamp = rq->idle_stamp;
+				shallowest_idle_cpu = i;
+			} else if ((!idle || idle->exit_latency == min_exit_latency) &&
+				   rq->idle_stamp > latest_idle_timestamp) {
+				/*
+				 * If equal or no active idle state, then
+				 * the most recently idled CPU might have
+				 * a warmer cache.
+				 */
+				latest_idle_timestamp = rq->idle_stamp;
+				shallowest_idle_cpu = i;
 			}
-
-			imbalance = abs(local_sgs.idle_cpus - idlest_sgs.idle_cpus);
-			if (!adjust_numa_imbalance(imbalance,
-						   local_sgs.sum_nr_running + 1,
-						   imb_numa_nr)) {
-				return NULL;
+		} else if (shallowest_idle_cpu == -1) {
+			load = cpu_load(cpu_rq(i));
+			if (load < min_load) {
+				min_load = load;
+				least_loaded_cpu = i;
 			}
 		}
-#endif /* CONFIG_NUMA */
-
-		/*
-		 * Select group with highest number of idle CPUs. We could also
-		 * compare the utilization which is more stable but it can end
-		 * up that the group has less spare capacity but finally more
-		 * idle CPUs which means more opportunity to run task.
-		 */
-		if (local_sgs.idle_cpus >= idlest_sgs.idle_cpus)
-			return NULL;
-		break;
 	}
 
-	return idlest;
+	return shallowest_idle_cpu != -1 ? shallowest_idle_cpu : least_loaded_cpu;
 }
 
-static void update_idle_cpu_scan(struct lb_env *env,
-				 unsigned long sum_util)
+static inline int sched_balance_find_dst_cpu(struct sched_domain *sd, struct task_struct *p,
+				  int cpu, int prev_cpu, int sd_flag)
 {
-	struct sched_domain_shared *sd_share;
-	int llc_weight, pct;
-	u64 x, y, tmp;
-	/*
-	 * Update the number of CPUs to scan in LLC domain, which could
-	 * be used as a hint in select_idle_cpu(). The update of sd_share
-	 * could be expensive because it is within a shared cache line.
-	 * So the write of this hint only occurs during periodic load
-	 * balancing, rather than CPU_NEWLY_IDLE, because the latter
-	 * can fire way more frequently than the former.
-	 */
-	if (!sched_feat(SIS_UTIL) || env->idle == CPU_NEWLY_IDLE)
-		return;
-
-	llc_weight = per_cpu(sd_llc_size, env->dst_cpu);
-	if (env->sd->span_weight != llc_weight)
-		return;
+	int new_cpu = cpu;
 
-	sd_share = rcu_dereference(per_cpu(sd_llc_shared, env->dst_cpu));
-	if (!sd_share)
-		return;
+	if (!cpumask_intersects(sched_domain_span(sd), p->cpus_ptr))
+		return prev_cpu;
 
 	/*
-	 * The number of CPUs to search drops as sum_util increases, when
-	 * sum_util hits 85% or above, the scan stops.
-	 * The reason to choose 85% as the threshold is because this is the
-	 * imbalance_pct(117) when a LLC sched group is overloaded.
-	 *
-	 * let y = SCHED_CAPACITY_SCALE - p * x^2                       [1]
-	 * and y'= y / SCHED_CAPACITY_SCALE
-	 *
-	 * x is the ratio of sum_util compared to the CPU capacity:
-	 * x = sum_util / (llc_weight * SCHED_CAPACITY_SCALE)
-	 * y' is the ratio of CPUs to be scanned in the LLC domain,
-	 * and the number of CPUs to scan is calculated by:
-	 *
-	 * nr_scan = llc_weight * y'                                    [2]
-	 *
-	 * When x hits the threshold of overloaded, AKA, when
-	 * x = 100 / pct, y drops to 0. According to [1],
-	 * p should be SCHED_CAPACITY_SCALE * pct^2 / 10000
-	 *
-	 * Scale x by SCHED_CAPACITY_SCALE:
-	 * x' = sum_util / llc_weight;                                  [3]
-	 *
-	 * and finally [1] becomes:
-	 * y = SCHED_CAPACITY_SCALE -
-	 *     x'^2 * pct^2 / (10000 * SCHED_CAPACITY_SCALE)            [4]
-	 *
+	 * We need task's util for cpu_util_without, sync it up to
+	 * prev_cpu's last_update_time.
 	 */
-	/* equation [3] */
-	x = sum_util;
-	do_div(x, llc_weight);
-
-	/* equation [4] */
-	pct = env->sd->imbalance_pct;
-	tmp = x * x * pct * pct;
-	do_div(tmp, 10000 * SCHED_CAPACITY_SCALE);
-	tmp = min_t(long, tmp, SCHED_CAPACITY_SCALE);
-	y = SCHED_CAPACITY_SCALE - tmp;
-
-	/* equation [2] */
-	y *= llc_weight;
-	do_div(y, SCHED_CAPACITY_SCALE);
-	if ((int)y != sd_share->nr_idle_scan)
-		WRITE_ONCE(sd_share->nr_idle_scan, (int)y);
-}
-
-/**
- * update_sd_lb_stats - Update sched_domain's statistics for load balancing.
- * @env: The load balancing environment.
- * @sds: variable to hold the statistics for this sched_domain.
- */
-
-static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sds)
-{
-	struct sched_group *sg = env->sd->groups;
-	struct sg_lb_stats *local = &sds->local_stat;
-	struct sg_lb_stats tmp_sgs;
-	unsigned long sum_util = 0;
-	bool sg_overloaded = 0, sg_overutilized = 0;
+	if (!(sd_flag & SD_BALANCE_FORK))
+		sync_entity_load_avg(&p->se);
 
-	do {
-		struct sg_lb_stats *sgs = &tmp_sgs;
-		int local_group;
+	while (sd) {
+		struct sched_group *group;
+		struct sched_domain *tmp;
+		int weight;
 
-		local_group = cpumask_test_cpu(env->dst_cpu, sched_group_span(sg));
-		if (local_group) {
-			sds->local = sg;
-			sgs = local;
+		if (!(sd->flags & sd_flag)) {
+			sd = sd->child;
+			continue;
+		}
 
-			if (env->idle != CPU_NEWLY_IDLE ||
-			    time_after_eq(jiffies, sg->sgc->next_update))
-				update_group_capacity(env->sd, env->dst_cpu);
+		group = sched_balance_find_dst_group(sd, p, cpu);
+		if (!group) {
+			sd = sd->child;
+			continue;
 		}
 
-		update_sg_lb_stats(env, sds, sg, sgs, &sg_overloaded, &sg_overutilized);
+		new_cpu = sched_balance_find_dst_group_cpu(group, p, cpu);
+		if (new_cpu == cpu) {
+			/* Now try balancing at a lower domain level of 'cpu': */
+			sd = sd->child;
+			continue;
+		}
 
-		if (!local_group && update_sd_pick_busiest(env, sds, sg, sgs)) {
-			sds->busiest = sg;
-			sds->busiest_stat = *sgs;
+		/* Now try balancing at a lower domain level of 'new_cpu': */
+		cpu = new_cpu;
+		weight = sd->span_weight;
+		sd = NULL;
+		for_each_domain(cpu, tmp) {
+			if (weight <= tmp->span_weight)
+				break;
+			if (tmp->flags & sd_flag)
+				sd = tmp;
 		}
+	}
+
+	return new_cpu;
+}
 
-		/* Now, start updating sd_lb_stats */
-		sds->total_load += sgs->group_load;
-		sds->total_capacity += sgs->group_capacity;
+static inline int __select_idle_cpu(int cpu, struct task_struct *p)
+{
+	if ((available_idle_cpu(cpu) || sched_idle_cpu(cpu)) &&
+	    sched_cpu_cookie_match(cpu_rq(cpu), p))
+		return cpu;
 
-		sum_util += sgs->group_util;
-		sg = sg->next;
-	} while (sg != env->sd->groups);
+	return -1;
+}
 
-	/*
-	 * Indicate that the child domain of the busiest group prefers tasks
-	 * go to a child's sibling domains first. NB the flags of a sched group
-	 * are those of the child domain.
-	 */
-	if (sds->busiest)
-		sds->prefer_sibling = !!(sds->busiest->flags & SD_PREFER_SIBLING);
+#ifdef CONFIG_SCHED_SMT
+DEFINE_STATIC_KEY_FALSE(sched_smt_present);
+EXPORT_SYMBOL_GPL(sched_smt_present);
 
+static inline void set_idle_cores(int cpu, int val)
+{
+	struct sched_domain_shared *sds;
 
-	if (env->sd->flags & SD_NUMA)
-		env->fbq_type = fbq_classify_group(&sds->busiest_stat);
+	sds = rcu_dereference(per_cpu(sd_llc_shared, cpu));
+	if (sds)
+		WRITE_ONCE(sds->has_idle_cores, val);
+}
 
-	if (!env->sd->parent) {
-		/* update overload indicator if we are at root domain */
-		set_rd_overloaded(env->dst_rq->rd, sg_overloaded);
+static inline bool test_idle_cores(int cpu)
+{
+	struct sched_domain_shared *sds;
 
-		/* Update over-utilization (tipping point, U >= 0) indicator */
-		set_rd_overutilized(env->dst_rq->rd, sg_overloaded);
-	} else if (sg_overutilized) {
-		set_rd_overutilized(env->dst_rq->rd, sg_overutilized);
-	}
+	sds = rcu_dereference(per_cpu(sd_llc_shared, cpu));
+	if (sds)
+		return READ_ONCE(sds->has_idle_cores);
 
-	update_idle_cpu_scan(env, sum_util);
+	return false;
 }
 
-/**
- * calculate_imbalance - Calculate the amount of imbalance present within the
- *			 groups of a given sched_domain during load balance.
- * @env: load balance environment
- * @sds: statistics of the sched_domain whose imbalance is to be calculated.
+/*
+ * Scans the local SMT mask to see if the entire core is idle, and records this
+ * information in sd_llc_shared->has_idle_cores.
+ *
+ * Since SMT siblings share all cache levels, inspecting this limited remote
+ * state should be fairly cheap.
  */
-static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
+void __update_idle_core(struct rq *rq)
 {
-	struct sg_lb_stats *local, *busiest;
-
-	local = &sds->local_stat;
-	busiest = &sds->busiest_stat;
+	int core = cpu_of(rq);
+	int cpu;
 
-	if (busiest->group_type == group_misfit_task) {
-		if (env->sd->flags & SD_ASYM_CPUCAPACITY) {
-			/* Set imbalance to allow misfit tasks to be balanced. */
-			env->migration_type = migrate_misfit;
-			env->imbalance = 1;
-		} else {
-			/*
-			 * Set load imbalance to allow moving task from cpu
-			 * with reduced capacity.
-			 */
-			env->migration_type = migrate_load;
-			env->imbalance = busiest->group_misfit_task_load;
-		}
-		return;
-	}
+	rcu_read_lock();
+	if (test_idle_cores(core))
+		goto unlock;
 
-	if (busiest->group_type == group_asym_packing) {
-		/*
-		 * In case of asym capacity, we will try to migrate all load to
-		 * the preferred CPU.
-		 */
-		env->migration_type = migrate_task;
-		env->imbalance = busiest->sum_h_nr_running;
-		return;
-	}
+	for_each_cpu(cpu, cpu_smt_mask(core)) {
+		if (cpu == core)
+			continue;
 
-	if (busiest->group_type == group_smt_balance) {
-		/* Reduce number of tasks sharing CPU capacity */
-		env->migration_type = migrate_task;
-		env->imbalance = 1;
-		return;
+		if (!available_idle_cpu(cpu))
+			goto unlock;
 	}
 
-	if (busiest->group_type == group_imbalanced) {
-		/*
-		 * In the group_imb case we cannot rely on group-wide averages
-		 * to ensure CPU-load equilibrium, try to move any task to fix
-		 * the imbalance. The next load balance will take care of
-		 * balancing back the system.
-		 */
-		env->migration_type = migrate_task;
-		env->imbalance = 1;
-		return;
-	}
+	set_idle_cores(core, 1);
+unlock:
+	rcu_read_unlock();
+}
 
-	/*
-	 * Try to use spare capacity of local group without overloading it or
-	 * emptying busiest.
-	 */
-	if (local->group_type == group_has_spare) {
-		if ((busiest->group_type > group_fully_busy) &&
-		    !(env->sd->flags & SD_SHARE_LLC)) {
-			/*
-			 * If busiest is overloaded, try to fill spare
-			 * capacity. This might end up creating spare capacity
-			 * in busiest or busiest still being overloaded but
-			 * there is no simple way to directly compute the
-			 * amount of load to migrate in order to balance the
-			 * system.
-			 */
-			env->migration_type = migrate_util;
-			env->imbalance = max(local->group_capacity, local->group_util) -
-					 local->group_util;
+/*
+ * Scan the entire LLC domain for idle cores; this dynamically switches off if
+ * there are no idle cores left in the system; tracked through
+ * sd_llc->shared->has_idle_cores and enabled through update_idle_core() above.
+ */
+static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu)
+{
+	bool idle = true;
+	int cpu;
 
-			/*
-			 * In some cases, the group's utilization is max or even
-			 * higher than capacity because of migrations but the
-			 * local CPU is (newly) idle. There is at least one
-			 * waiting task in this overloaded busiest group. Let's
-			 * try to pull it.
-			 */
-			if (env->idle && env->imbalance == 0) {
-				env->migration_type = migrate_task;
-				env->imbalance = 1;
+	for_each_cpu(cpu, cpu_smt_mask(core)) {
+		if (!available_idle_cpu(cpu)) {
+			idle = false;
+			if (*idle_cpu == -1) {
+				if (sched_idle_cpu(cpu) && cpumask_test_cpu(cpu, cpus)) {
+					*idle_cpu = cpu;
+					break;
+				}
+				continue;
 			}
-
-			return;
-		}
-
-		if (busiest->group_weight == 1 || sds->prefer_sibling) {
-			/*
-			 * When prefer sibling, evenly spread running tasks on
-			 * groups.
-			 */
-			env->migration_type = migrate_task;
-			env->imbalance = sibling_imbalance(env, sds, busiest, local);
-		} else {
-
-			/*
-			 * If there is no overload, we just want to even the number of
-			 * idle CPUs.
-			 */
-			env->migration_type = migrate_task;
-			env->imbalance = max_t(long, 0,
-					       (local->idle_cpus - busiest->idle_cpus));
-		}
-
-#ifdef CONFIG_NUMA
-		/* Consider allowing a small imbalance between NUMA groups */
-		if (env->sd->flags & SD_NUMA) {
-			env->imbalance = adjust_numa_imbalance(env->imbalance,
-							       local->sum_nr_running + 1,
-							       env->sd->imb_numa_nr);
+			break;
 		}
-#endif
-
-		/* Number of tasks to move to restore balance */
-		env->imbalance >>= 1;
-
-		return;
+		if (*idle_cpu == -1 && cpumask_test_cpu(cpu, cpus))
+			*idle_cpu = cpu;
 	}
 
-	/*
-	 * Local is fully busy but has to take more load to relieve the
-	 * busiest group
-	 */
-	if (local->group_type < group_overloaded) {
-		/*
-		 * Local will become overloaded so the avg_load metrics are
-		 * finally needed.
-		 */
-
-		local->avg_load = (local->group_load * SCHED_CAPACITY_SCALE) /
-				  local->group_capacity;
+	if (idle)
+		return core;
 
-		/*
-		 * If the local group is more loaded than the selected
-		 * busiest group don't try to pull any tasks.
-		 */
-		if (local->avg_load >= busiest->avg_load) {
-			env->imbalance = 0;
-			return;
-		}
+	cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
+	return -1;
+}
 
-		sds->avg_load = (sds->total_load * SCHED_CAPACITY_SCALE) /
-				sds->total_capacity;
+/*
+ * Scan the local SMT mask for idle CPUs.
+ */
+static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
+{
+	int cpu;
 
+	for_each_cpu_and(cpu, cpu_smt_mask(target), p->cpus_ptr) {
+		if (cpu == target)
+			continue;
 		/*
-		 * If the local group is more loaded than the average system
-		 * load, don't try to pull any tasks.
+		 * Check if the CPU is in the LLC scheduling domain of @target.
+		 * Due to isolcpus, there is no guarantee that all the siblings are in the domain.
 		 */
-		if (local->avg_load >= sds->avg_load) {
-			env->imbalance = 0;
-			return;
-		}
-
+		if (!cpumask_test_cpu(cpu, sched_domain_span(sd)))
+			continue;
+		if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
+			return cpu;
 	}
 
-	/*
-	 * Both group are or will become overloaded and we're trying to get all
-	 * the CPUs to the average_load, so we don't want to push ourselves
-	 * above the average load, nor do we wish to reduce the max loaded CPU
-	 * below the average load. At the same time, we also don't want to
-	 * reduce the group load below the group capacity. Thus we look for
-	 * the minimum possible imbalance.
-	 */
-	env->migration_type = migrate_load;
-	env->imbalance = min(
-		(busiest->avg_load - sds->avg_load) * busiest->group_capacity,
-		(sds->avg_load - local->avg_load) * local->group_capacity
-	) / SCHED_CAPACITY_SCALE;
+	return -1;
 }
 
-/******* sched_balance_find_src_group() helpers end here *********************/
-
-/*
- * Decision matrix according to the local and busiest group type:
- *
- * busiest \ local has_spare fully_busy misfit asym imbalanced overloaded
- * has_spare        nr_idle   balanced   N/A    N/A  balanced   balanced
- * fully_busy       nr_idle   nr_idle    N/A    N/A  balanced   balanced
- * misfit_task      force     N/A        N/A    N/A  N/A        N/A
- * asym_packing     force     force      N/A    N/A  force      force
- * imbalanced       force     force      N/A    N/A  force      force
- * overloaded       force     force      N/A    N/A  force      avg_load
- *
- * N/A :      Not Applicable because already filtered while updating
- *            statistics.
- * balanced : The system is balanced for these 2 groups.
- * force :    Calculate the imbalance as load migration is probably needed.
- * avg_load : Only if imbalance is significant enough.
- * nr_idle :  dst_cpu is not busy and the number of idle CPUs is quite
- *            different in groups.
- */
+#else /* CONFIG_SCHED_SMT */
 
-/**
- * sched_balance_find_src_group - Returns the busiest group within the sched_domain
- * if there is an imbalance.
- * @env: The load balancing environment.
- *
- * Also calculates the amount of runnable load which should be moved
- * to restore balance.
- *
- * Return:	- The busiest group if imbalance exists.
- */
-static struct sched_group *sched_balance_find_src_group(struct lb_env *env)
+static inline void set_idle_cores(int cpu, int val)
 {
-	struct sg_lb_stats *local, *busiest;
-	struct sd_lb_stats sds;
-
-	init_sd_lb_stats(&sds);
-
-	/*
-	 * Compute the various statistics relevant for load balancing at
-	 * this level.
-	 */
-	update_sd_lb_stats(env, &sds);
-
-	/* There is no busy sibling group to pull tasks from */
-	if (!sds.busiest)
-		goto out_balanced;
-
-	busiest = &sds.busiest_stat;
-
-	/* Misfit tasks should be dealt with regardless of the avg load */
-	if (busiest->group_type == group_misfit_task)
-		goto force_balance;
-
-	if (!is_rd_overutilized(env->dst_rq->rd) &&
-	    rcu_dereference(env->dst_rq->rd->pd))
-		goto out_balanced;
+}
 
-	/* ASYM feature bypasses nice load balance check */
-	if (busiest->group_type == group_asym_packing)
-		goto force_balance;
+static inline bool test_idle_cores(int cpu)
+{
+	return false;
+}
 
-	/*
-	 * If the busiest group is imbalanced the below checks don't
-	 * work because they assume all things are equal, which typically
-	 * isn't true due to cpus_ptr constraints and the like.
-	 */
-	if (busiest->group_type == group_imbalanced)
-		goto force_balance;
+static inline int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu)
+{
+	return __select_idle_cpu(core, p);
+}
 
-	local = &sds.local_stat;
-	/*
-	 * If the local group is busier than the selected busiest group
-	 * don't try and pull any tasks.
-	 */
-	if (local->group_type > busiest->group_type)
-		goto out_balanced;
+static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
+{
+	return -1;
+}
 
-	/*
-	 * When groups are overloaded, use the avg_load to ensure fairness
-	 * between tasks.
-	 */
-	if (local->group_type == group_overloaded) {
-		/*
-		 * If the local group is more loaded than the selected
-		 * busiest group don't try to pull any tasks.
-		 */
-		if (local->avg_load >= busiest->avg_load)
-			goto out_balanced;
+#endif /* CONFIG_SCHED_SMT */
 
-		/* XXX broken for overlapping NUMA groups */
-		sds.avg_load = (sds.total_load * SCHED_CAPACITY_SCALE) /
-				sds.total_capacity;
+/*
+ * Scan the LLC domain for idle CPUs; this is dynamically regulated by
+ * comparing the average scan cost (tracked in sd->avg_scan_cost) against the
+ * average idle time for this rq (as found in rq->avg_idle).
+ */
+static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool has_idle_core, int target)
+{
+	struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
+	int i, cpu, idle_cpu = -1, nr = INT_MAX;
+	struct sched_domain_shared *sd_share;
 
-		/*
-		 * Don't pull any tasks if this group is already above the
-		 * domain average load.
-		 */
-		if (local->avg_load >= sds.avg_load)
-			goto out_balanced;
+	cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
 
-		/*
-		 * If the busiest group is more loaded, use imbalance_pct to be
-		 * conservative.
-		 */
-		if (100 * busiest->avg_load <=
-				env->sd->imbalance_pct * local->avg_load)
-			goto out_balanced;
+	if (sched_feat(SIS_UTIL)) {
+		sd_share = rcu_dereference(per_cpu(sd_llc_shared, target));
+		if (sd_share) {
+			/* because !--nr is the condition to stop scan */
+			nr = READ_ONCE(sd_share->nr_idle_scan) + 1;
+			/* overloaded LLC is unlikely to have idle cpu/core */
+			if (nr == 1)
+				return -1;
+		}
 	}
 
-	/*
-	 * Try to move all excess tasks to a sibling domain of the busiest
-	 * group's child domain.
-	 */
-	if (sds.prefer_sibling && local->group_type == group_has_spare &&
-	    sibling_imbalance(env, &sds, busiest, local) > 1)
-		goto force_balance;
+	if (static_branch_unlikely(&sched_cluster_active)) {
+		struct sched_group *sg = sd->groups;
 
-	if (busiest->group_type != group_overloaded) {
-		if (!env->idle) {
-			/*
-			 * If the busiest group is not overloaded (and as a
-			 * result the local one too) but this CPU is already
-			 * busy, let another idle CPU try to pull task.
-			 */
-			goto out_balanced;
-		}
+		if (sg->flags & SD_CLUSTER) {
+			for_each_cpu_wrap(cpu, sched_group_span(sg), target + 1) {
+				if (!cpumask_test_cpu(cpu, cpus))
+					continue;
 
-		if (busiest->group_type == group_smt_balance &&
-		    smt_vs_nonsmt_groups(sds.local, sds.busiest)) {
-			/* Let non SMT CPU pull from SMT CPU sharing with sibling */
-			goto force_balance;
+				if (has_idle_core) {
+					i = select_idle_core(p, cpu, cpus, &idle_cpu);
+					if ((unsigned int)i < nr_cpumask_bits)
+						return i;
+				} else {
+					if (--nr <= 0)
+						return -1;
+					idle_cpu = __select_idle_cpu(cpu, p);
+					if ((unsigned int)idle_cpu < nr_cpumask_bits)
+						return idle_cpu;
+				}
+			}
+			cpumask_andnot(cpus, cpus, sched_group_span(sg));
 		}
+	}
 
-		if (busiest->group_weight > 1 &&
-		    local->idle_cpus <= (busiest->idle_cpus + 1)) {
-			/*
-			 * If the busiest group is not overloaded
-			 * and there is no imbalance between this and busiest
-			 * group wrt idle CPUs, it is balanced. The imbalance
-			 * becomes significant if the diff is greater than 1
-			 * otherwise we might end up to just move the imbalance
-			 * on another group. Of course this applies only if
-			 * there is more than 1 CPU per group.
-			 */
-			goto out_balanced;
-		}
+	for_each_cpu_wrap(cpu, cpus, target + 1) {
+		if (has_idle_core) {
+			i = select_idle_core(p, cpu, cpus, &idle_cpu);
+			if ((unsigned int)i < nr_cpumask_bits)
+				return i;
 
-		if (busiest->sum_h_nr_running == 1) {
-			/*
-			 * busiest doesn't have any tasks waiting to run
-			 */
-			goto out_balanced;
+		} else {
+			if (--nr <= 0)
+				return -1;
+			idle_cpu = __select_idle_cpu(cpu, p);
+			if ((unsigned int)idle_cpu < nr_cpumask_bits)
+				break;
 		}
 	}
 
-force_balance:
-	/* Looks like there is an imbalance. Compute it */
-	calculate_imbalance(env, &sds);
-	return env->imbalance ? sds.busiest : NULL;
+	if (has_idle_core)
+		set_idle_cores(target, false);
 
-out_balanced:
-	env->imbalance = 0;
-	return NULL;
+	return idle_cpu;
 }
 
 /*
- * sched_balance_find_src_rq - find the busiest runqueue among the CPUs in the group.
+ * Scan the asym_capacity domain for idle CPUs; pick the first idle one on which
+ * the task fits. If no CPU is big enough, but there are idle ones, try to
+ * maximize capacity.
  */
-static struct rq *sched_balance_find_src_rq(struct lb_env *env,
-				     struct sched_group *group)
+static int
+select_idle_capacity(struct task_struct *p, struct sched_domain *sd, int target)
 {
-	struct rq *busiest = NULL, *rq;
-	unsigned long busiest_util = 0, busiest_load = 0, busiest_capacity = 1;
-	unsigned int busiest_nr = 0;
-	int i;
-
-	for_each_cpu_and(i, sched_group_span(group), env->cpus) {
-		unsigned long capacity, load, util;
-		unsigned int nr_running;
-		enum fbq_type rt;
-
-		rq = cpu_rq(i);
-		rt = fbq_classify_rq(rq);
+	unsigned long task_util, util_min, util_max, best_cap = 0;
+	int fits, best_fits = 0;
+	int cpu, best_cpu = -1;
+	struct cpumask *cpus;
 
-		/*
-		 * We classify groups/runqueues into three groups:
-		 *  - regular: there are !numa tasks
-		 *  - remote:  there are numa tasks that run on the 'wrong' node
-		 *  - all:     there is no distinction
-		 *
-		 * In order to avoid migrating ideally placed numa tasks,
-		 * ignore those when there's better options.
-		 *
-		 * If we ignore the actual busiest queue to migrate another
-		 * task, the next balance pass can still reduce the busiest
-		 * queue by moving tasks around inside the node.
-		 *
-		 * If we cannot move enough load due to this classification
-		 * the next pass will adjust the group classification and
-		 * allow migration of more tasks.
-		 *
-		 * Both cases only affect the total convergence complexity.
-		 */
-		if (rt > env->fbq_type)
-			continue;
+	cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
+	cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
+
+	task_util = task_util_est(p);
+	util_min = uclamp_eff_value(p, UCLAMP_MIN);
+	util_max = uclamp_eff_value(p, UCLAMP_MAX);
+
+	for_each_cpu_wrap(cpu, cpus, target) {
+		unsigned long cpu_cap = capacity_of(cpu);
 
-		nr_running = rq->cfs.h_nr_running;
-		if (!nr_running)
+		if (!available_idle_cpu(cpu) && !sched_idle_cpu(cpu))
 			continue;
 
-		capacity = capacity_of(i);
+		fits = util_fits_cpu(task_util, util_min, util_max, cpu);
 
+		/* This CPU fits with all requirements */
+		if (fits > 0)
+			return cpu;
 		/*
-		 * For ASYM_CPUCAPACITY domains, don't pick a CPU that could
-		 * eventually lead to active_balancing high->low capacity.
-		 * Higher per-CPU capacity is considered better than balancing
-		 * average load.
+		 * Only the min performance hint (i.e. uclamp_min) doesn't fit.
+		 * Look for the CPU with best capacity.
 		 */
-		if (env->sd->flags & SD_ASYM_CPUCAPACITY &&
-		    !capacity_greater(capacity_of(env->dst_cpu), capacity) &&
-		    nr_running == 1)
-			continue;
+		else if (fits < 0)
+			cpu_cap = arch_scale_cpu_capacity(cpu) - thermal_load_avg(cpu_rq(cpu));
 
 		/*
-		 * Make sure we only pull tasks from a CPU of lower priority
-		 * when balancing between SMT siblings.
-		 *
-		 * If balancing between cores, let lower priority CPUs help
-		 * SMT cores with more than one busy sibling.
+		 * First, select CPU which fits better (-1 being better than 0).
+		 * Then, select the one with best capacity at same level.
 		 */
-		if (sched_asym(env->sd, i, env->dst_cpu) && nr_running == 1)
-			continue;
-
-		switch (env->migration_type) {
-		case migrate_load:
-			/*
-			 * When comparing with load imbalance, use cpu_load()
-			 * which is not scaled with the CPU capacity.
-			 */
-			load = cpu_load(rq);
-
-			if (nr_running == 1 && load > env->imbalance &&
-			    !check_cpu_capacity(rq, env->sd))
-				break;
-
-			/*
-			 * For the load comparisons with the other CPUs,
-			 * consider the cpu_load() scaled with the CPU
-			 * capacity, so that the load can be moved away
-			 * from the CPU that is potentially running at a
-			 * lower capacity.
-			 *
-			 * Thus we're looking for max(load_i / capacity_i),
-			 * crosswise multiplication to rid ourselves of the
-			 * division works out to:
-			 * load_i * capacity_j > load_j * capacity_i;
-			 * where j is our previous maximum.
-			 */
-			if (load * busiest_capacity > busiest_load * capacity) {
-				busiest_load = load;
-				busiest_capacity = capacity;
-				busiest = rq;
-			}
-			break;
-
-		case migrate_util:
-			util = cpu_util_cfs_boost(i);
-
-			/*
-			 * Don't try to pull utilization from a CPU with one
-			 * running task. Whatever its utilization, we will fail
-			 * detach the task.
-			 */
-			if (nr_running <= 1)
-				continue;
-
-			if (busiest_util < util) {
-				busiest_util = util;
-				busiest = rq;
-			}
-			break;
-
-		case migrate_task:
-			if (busiest_nr < nr_running) {
-				busiest_nr = nr_running;
-				busiest = rq;
-			}
-			break;
-
-		case migrate_misfit:
-			/*
-			 * For ASYM_CPUCAPACITY domains with misfit tasks we
-			 * simply seek the "biggest" misfit task.
-			 */
-			if (rq->misfit_task_load > busiest_load) {
-				busiest_load = rq->misfit_task_load;
-				busiest = rq;
-			}
-
-			break;
-
+		if ((fits < best_fits) ||
+		    ((fits == best_fits) && (cpu_cap > best_cap))) {
+			best_cap = cpu_cap;
+			best_cpu = cpu;
+			best_fits = fits;
 		}
 	}
 
-	return busiest;
+	return best_cpu;
+}
+
+static inline bool asym_fits_cpu(unsigned long util,
+				 unsigned long util_min,
+				 unsigned long util_max,
+				 int cpu)
+{
+	if (sched_asym_cpucap_active())
+		/*
+		 * Return true only if the cpu fully fits the task requirements
+		 * which include the utilization and the performance hints.
+		 */
+		return (util_fits_cpu(util, util_min, util_max, cpu) > 0);
+
+	return true;
 }
 
 /*
- * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
- * so long as it is large enough.
+ * Try and locate an idle core/thread in the LLC cache domain.
  */
-#define MAX_PINNED_INTERVAL	512
-
-static inline bool
-asym_active_balance(struct lb_env *env)
+static int select_idle_sibling(struct task_struct *p, int prev, int target)
 {
+	bool has_idle_core = false;
+	struct sched_domain *sd;
+	unsigned long task_util, util_min, util_max;
+	int i, recent_used_cpu, prev_aff = -1;
+
 	/*
-	 * ASYM_PACKING needs to force migrate tasks from busy but lower
-	 * priority CPUs in order to pack all tasks in the highest priority
-	 * CPUs. When done between cores, do it only if the whole core if the
-	 * whole core is idle.
-	 *
-	 * If @env::src_cpu is an SMT core with busy siblings, let
-	 * the lower priority @env::dst_cpu help it. Do not follow
-	 * CPU priority.
+	 * On asymmetric system, update task utilization because we will check
+	 * that the task fits with CPU's capacity.
 	 */
-	return env->idle && sched_use_asym_prio(env->sd, env->dst_cpu) &&
-	       (sched_asym_prefer(env->dst_cpu, env->src_cpu) ||
-		!sched_use_asym_prio(env->sd, env->src_cpu));
-}
-
-static inline bool
-imbalanced_active_balance(struct lb_env *env)
-{
-	struct sched_domain *sd = env->sd;
+	if (sched_asym_cpucap_active()) {
+		sync_entity_load_avg(&p->se);
+		task_util = task_util_est(p);
+		util_min = uclamp_eff_value(p, UCLAMP_MIN);
+		util_max = uclamp_eff_value(p, UCLAMP_MAX);
+	}
 
 	/*
-	 * The imbalanced case includes the case of pinned tasks preventing a fair
-	 * distribution of the load on the system but also the even distribution of the
-	 * threads on a system with spare capacity
+	 * per-cpu select_rq_mask usage
 	 */
-	if ((env->migration_type == migrate_task) &&
-	    (sd->nr_balance_failed > sd->cache_nice_tries+2))
-		return 1;
+	lockdep_assert_irqs_disabled();
 
-	return 0;
-}
+	if ((available_idle_cpu(target) || sched_idle_cpu(target)) &&
+	    asym_fits_cpu(task_util, util_min, util_max, target))
+		return target;
 
-static int need_active_balance(struct lb_env *env)
-{
-	struct sched_domain *sd = env->sd;
+	/*
+	 * If the previous CPU is cache affine and idle, don't be stupid:
+	 */
+	if (prev != target && cpus_share_cache(prev, target) &&
+	    (available_idle_cpu(prev) || sched_idle_cpu(prev)) &&
+	    asym_fits_cpu(task_util, util_min, util_max, prev)) {
 
-	if (asym_active_balance(env))
-		return 1;
+		if (!static_branch_unlikely(&sched_cluster_active) ||
+		    cpus_share_resources(prev, target))
+			return prev;
 
-	if (imbalanced_active_balance(env))
-		return 1;
+		prev_aff = prev;
+	}
 
 	/*
-	 * The dst_cpu is idle and the src_cpu CPU has only 1 CFS task.
-	 * It's worth migrating the task if the src_cpu's capacity is reduced
-	 * because of other sched_class or IRQs if more capacity stays
-	 * available on dst_cpu.
+	 * Allow a per-cpu kthread to stack with the wakee if the
+	 * kworker thread and the tasks previous CPUs are the same.
+	 * The assumption is that the wakee queued work for the
+	 * per-cpu kthread that is now complete and the wakeup is
+	 * essentially a sync wakeup. An obvious example of this
+	 * pattern is IO completions.
 	 */
-	if (env->idle &&
-	    (env->src_rq->cfs.h_nr_running == 1)) {
-		if ((check_cpu_capacity(env->src_rq, sd)) &&
-		    (capacity_of(env->src_cpu)*sd->imbalance_pct < capacity_of(env->dst_cpu)*100))
-			return 1;
+	if (is_per_cpu_kthread(current) &&
+	    in_task() &&
+	    prev == smp_processor_id() &&
+	    this_rq()->nr_running <= 1 &&
+	    asym_fits_cpu(task_util, util_min, util_max, prev)) {
+		return prev;
 	}
 
-	if (env->migration_type == migrate_misfit)
-		return 1;
-
-	return 0;
-}
-
-static int active_load_balance_cpu_stop(void *data);
+	/* Check a recently used CPU as a potential idle candidate: */
+	recent_used_cpu = p->recent_used_cpu;
+	p->recent_used_cpu = prev;
+	if (recent_used_cpu != prev &&
+	    recent_used_cpu != target &&
+	    cpus_share_cache(recent_used_cpu, target) &&
+	    (available_idle_cpu(recent_used_cpu) || sched_idle_cpu(recent_used_cpu)) &&
+	    cpumask_test_cpu(recent_used_cpu, p->cpus_ptr) &&
+	    asym_fits_cpu(task_util, util_min, util_max, recent_used_cpu)) {
 
-static int should_we_balance(struct lb_env *env)
-{
-	struct cpumask *swb_cpus = this_cpu_cpumask_var_ptr(should_we_balance_tmpmask);
-	struct sched_group *sg = env->sd->groups;
-	int cpu, idle_smt = -1;
+		if (!static_branch_unlikely(&sched_cluster_active) ||
+		    cpus_share_resources(recent_used_cpu, target))
+			return recent_used_cpu;
 
-	/*
-	 * Ensure the balancing environment is consistent; can happen
-	 * when the softirq triggers 'during' hotplug.
-	 */
-	if (!cpumask_test_cpu(env->dst_cpu, env->cpus))
-		return 0;
+	} else {
+		recent_used_cpu = -1;
+	}
 
 	/*
-	 * In the newly idle case, we will allow all the CPUs
-	 * to do the newly idle load balance.
-	 *
-	 * However, we bail out if we already have tasks or a wakeup pending,
-	 * to optimize wakeup latency.
+	 * For asymmetric CPU capacity systems, our domain of interest is
+	 * sd_asym_cpucapacity rather than sd_llc.
 	 */
-	if (env->idle == CPU_NEWLY_IDLE) {
-		if (env->dst_rq->nr_running > 0 || env->dst_rq->ttwu_pending)
-			return 0;
-		return 1;
-	}
-
-	cpumask_copy(swb_cpus, group_balance_mask(sg));
-	/* Try to find first idle CPU */
-	for_each_cpu_and(cpu, swb_cpus, env->cpus) {
-		if (!idle_cpu(cpu))
-			continue;
-
+	if (sched_asym_cpucap_active()) {
+		sd = rcu_dereference(per_cpu(sd_asym_cpucapacity, target));
 		/*
-		 * Don't balance to idle SMT in busy core right away when
-		 * balancing cores, but remember the first idle SMT CPU for
-		 * later consideration.  Find CPU on an idle core first.
+		 * On an asymmetric CPU capacity system where an exclusive
+		 * cpuset defines a symmetric island (i.e. one unique
+		 * capacity_orig value through the cpuset), the key will be set
+		 * but the CPUs within that cpuset will not have a domain with
+		 * SD_ASYM_CPUCAPACITY. These should follow the usual symmetric
+		 * capacity path.
 		 */
-		if (!(env->sd->flags & SD_SHARE_CPUCAPACITY) && !is_core_idle(cpu)) {
-			if (idle_smt == -1)
-				idle_smt = cpu;
-			/*
-			 * If the core is not idle, and first SMT sibling which is
-			 * idle has been found, then its not needed to check other
-			 * SMT siblings for idleness:
-			 */
-#ifdef CONFIG_SCHED_SMT
-			cpumask_andnot(swb_cpus, swb_cpus, cpu_smt_mask(cpu));
-#endif
-			continue;
+		if (sd) {
+			i = select_idle_capacity(p, sd, target);
+			return ((unsigned)i < nr_cpumask_bits) ? i : target;
 		}
-
-		/*
-		 * Are we the first idle core in a non-SMT domain or higher,
-		 * or the first idle CPU in a SMT domain?
-		 */
-		return cpu == env->dst_cpu;
 	}
 
-	/* Are we the first idle CPU with busy siblings? */
-	if (idle_smt != -1)
-		return idle_smt == env->dst_cpu;
+	sd = rcu_dereference(per_cpu(sd_llc, target));
+	if (!sd)
+		return target;
 
-	/* Are we the first CPU of this group ? */
-	return group_balance_cpu(sg) == env->dst_cpu;
-}
+	if (sched_smt_active()) {
+		has_idle_core = test_idle_cores(target);
 
-/*
- * Check this_cpu to ensure it is balanced within domain. Attempt to move
- * tasks if there is an imbalance.
- */
-static int sched_balance_rq(int this_cpu, struct rq *this_rq,
-			struct sched_domain *sd, enum cpu_idle_type idle,
-			int *continue_balancing)
-{
-	int ld_moved, cur_ld_moved, active_balance = 0;
-	struct sched_domain *sd_parent = sd->parent;
-	struct sched_group *group;
-	struct rq *busiest;
-	struct rq_flags rf;
-	struct cpumask *cpus = this_cpu_cpumask_var_ptr(load_balance_mask);
-	struct lb_env env = {
-		.sd		= sd,
-		.dst_cpu	= this_cpu,
-		.dst_rq		= this_rq,
-		.dst_grpmask    = group_balance_mask(sd->groups),
-		.idle		= idle,
-		.loop_break	= SCHED_NR_MIGRATE_BREAK,
-		.cpus		= cpus,
-		.fbq_type	= all,
-		.tasks		= LIST_HEAD_INIT(env.tasks),
-	};
+		if (!has_idle_core && cpus_share_cache(prev, target)) {
+			i = select_idle_smt(p, sd, prev);
+			if ((unsigned int)i < nr_cpumask_bits)
+				return i;
+		}
+	}
 
-	cpumask_and(cpus, sched_domain_span(sd), cpu_active_mask);
+	i = select_idle_cpu(p, sd, has_idle_core, target);
+	if ((unsigned)i < nr_cpumask_bits)
+		return i;
 
-	schedstat_inc(sd->lb_count[idle]);
+	/*
+	 * For cluster machines which have lower sharing cache like L2 or
+	 * LLC Tag, we tend to find an idle CPU in the target's cluster
+	 * first. But prev_cpu or recent_used_cpu may also be a good candidate,
+	 * use them if possible when no idle CPU found in select_idle_cpu().
+	 */
+	if ((unsigned int)prev_aff < nr_cpumask_bits)
+		return prev_aff;
+	if ((unsigned int)recent_used_cpu < nr_cpumask_bits)
+		return recent_used_cpu;
 
-redo:
-	if (!should_we_balance(&env)) {
-		*continue_balancing = 0;
-		goto out_balanced;
-	}
+	return target;
+}
 
-	group = sched_balance_find_src_group(&env);
-	if (!group) {
-		schedstat_inc(sd->lb_nobusyg[idle]);
-		goto out_balanced;
-	}
+/**
+ * cpu_util() - Estimates the amount of CPU capacity used by CFS tasks.
+ * @cpu: the CPU to get the utilization for
+ * @p: task for which the CPU utilization should be predicted or NULL
+ * @dst_cpu: CPU @p migrates to, -1 if @p moves from @cpu or @p == NULL
+ * @boost: 1 to enable boosting, otherwise 0
+ *
+ * The unit of the return value must be the same as the one of CPU capacity
+ * so that CPU utilization can be compared with CPU capacity.
+ *
+ * CPU utilization is the sum of running time of runnable tasks plus the
+ * recent utilization of currently non-runnable tasks on that CPU.
+ * It represents the amount of CPU capacity currently used by CFS tasks in
+ * the range [0..max CPU capacity] with max CPU capacity being the CPU
+ * capacity at f_max.
+ *
+ * The estimated CPU utilization is defined as the maximum between CPU
+ * utilization and sum of the estimated utilization of the currently
+ * runnable tasks on that CPU. It preserves a utilization "snapshot" of
+ * previously-executed tasks, which helps better deduce how busy a CPU will
+ * be when a long-sleeping task wakes up. The contribution to CPU utilization
+ * of such a task would be significantly decayed at this point of time.
+ *
+ * Boosted CPU utilization is defined as max(CPU runnable, CPU utilization).
+ * CPU contention for CFS tasks can be detected by CPU runnable > CPU
+ * utilization. Boosting is implemented in cpu_util() so that internal
+ * users (e.g. EAS) can use it next to external users (e.g. schedutil),
+ * latter via cpu_util_cfs_boost().
+ *
+ * CPU utilization can be higher than the current CPU capacity
+ * (f_curr/f_max * max CPU capacity) or even the max CPU capacity because
+ * of rounding errors as well as task migrations or wakeups of new tasks.
+ * CPU utilization has to be capped to fit into the [0..max CPU capacity]
+ * range. Otherwise a group of CPUs (CPU0 util = 121% + CPU1 util = 80%)
+ * could be seen as over-utilized even though CPU1 has 20% of spare CPU
+ * capacity. CPU utilization is allowed to overshoot current CPU capacity
+ * though since this is useful for predicting the CPU capacity required
+ * after task migrations (scheduler-driven DVFS).
+ *
+ * Return: (Boosted) (estimated) utilization for the specified CPU.
+ */
+static unsigned long
+cpu_util(int cpu, struct task_struct *p, int dst_cpu, int boost)
+{
+	struct cfs_rq *cfs_rq = &cpu_rq(cpu)->cfs;
+	unsigned long util = READ_ONCE(cfs_rq->avg.util_avg);
+	unsigned long runnable;
 
-	busiest = sched_balance_find_src_rq(&env, group);
-	if (!busiest) {
-		schedstat_inc(sd->lb_nobusyq[idle]);
-		goto out_balanced;
+	if (boost) {
+		runnable = READ_ONCE(cfs_rq->avg.runnable_avg);
+		util = max(util, runnable);
 	}
 
-	WARN_ON_ONCE(busiest == env.dst_rq);
+	/*
+	 * If @dst_cpu is -1 or @p migrates from @cpu to @dst_cpu remove its
+	 * contribution. If @p migrates from another CPU to @cpu add its
+	 * contribution. In all the other cases @cpu is not impacted by the
+	 * migration so its util_avg is already correct.
+	 */
+	if (p && task_cpu(p) == cpu && dst_cpu != cpu)
+		lsub_positive(&util, task_util(p));
+	else if (p && task_cpu(p) != cpu && dst_cpu == cpu)
+		util += task_util(p);
 
-	schedstat_add(sd->lb_imbalance[idle], env.imbalance);
+	if (sched_feat(UTIL_EST)) {
+		unsigned long util_est;
 
-	env.src_cpu = busiest->cpu;
-	env.src_rq = busiest;
+		util_est = READ_ONCE(cfs_rq->avg.util_est);
 
-	ld_moved = 0;
-	/* Clear this flag as soon as we find a pullable task */
-	env.flags |= LBF_ALL_PINNED;
-	if (busiest->nr_running > 1) {
 		/*
-		 * Attempt to move tasks. If sched_balance_find_src_group has found
-		 * an imbalance but busiest->nr_running <= 1, the group is
-		 * still unbalanced. ld_moved simply stays zero, so it is
-		 * correctly treated as an imbalance.
+		 * During wake-up @p isn't enqueued yet and doesn't contribute
+		 * to any cpu_rq(cpu)->cfs.avg.util_est.
+		 * If @dst_cpu == @cpu add it to "simulate" cpu_util after @p
+		 * has been enqueued.
+		 *
+		 * During exec (@dst_cpu = -1) @p is enqueued and does
+		 * contribute to cpu_rq(cpu)->cfs.util_est.
+		 * Remove it to "simulate" cpu_util without @p's contribution.
+		 *
+		 * Despite the task_on_rq_queued(@p) check there is still a
+		 * small window for a possible race when an exec
+		 * select_task_rq_fair() races with LB's detach_task().
+		 *
+		 *   detach_task()
+		 *     deactivate_task()
+		 *       p->on_rq = TASK_ON_RQ_MIGRATING;
+		 *       -------------------------------- A
+		 *       dequeue_task()                    \
+		 *         dequeue_task_fair()              + Race Time
+		 *           util_est_dequeue()            /
+		 *       -------------------------------- B
+		 *
+		 * The additional check "current == p" is required to further
+		 * reduce the race window.
 		 */
-		env.loop_max  = min(sysctl_sched_nr_migrate, busiest->nr_running);
-
-more_balance:
-		rq_lock_irqsave(busiest, &rf);
-		update_rq_clock(busiest);
+		if (dst_cpu == cpu)
+			util_est += _task_util_est(p);
+		else if (p && unlikely(task_on_rq_queued(p) || current == p))
+			lsub_positive(&util_est, _task_util_est(p));
 
-		/*
-		 * cur_ld_moved - load moved in current iteration
-		 * ld_moved     - cumulative load moved across iterations
-		 */
-		cur_ld_moved = detach_tasks(&env);
+		util = max(util, util_est);
+	}
 
-		/*
-		 * We've detached some tasks from busiest_rq. Every
-		 * task is masked "TASK_ON_RQ_MIGRATING", so we can safely
-		 * unlock busiest->lock, and we are able to be sure
-		 * that nobody can manipulate the tasks in parallel.
-		 * See task_rq_lock() family for the details.
-		 */
+	return min(util, arch_scale_cpu_capacity(cpu));
+}
 
-		rq_unlock(busiest, &rf);
+unsigned long cpu_util_cfs(int cpu)
+{
+	return cpu_util(cpu, NULL, -1, 0);
+}
 
-		if (cur_ld_moved) {
-			attach_tasks(&env);
-			ld_moved += cur_ld_moved;
-		}
+unsigned long cpu_util_cfs_boost(int cpu)
+{
+	return cpu_util(cpu, NULL, -1, 1);
+}
 
-		local_irq_restore(rf.flags);
+/*
+ * cpu_util_without: compute cpu utilization without any contributions from *p
+ * @cpu: the CPU which utilization is requested
+ * @p: the task which utilization should be discounted
+ *
+ * The utilization of a CPU is defined by the utilization of tasks currently
+ * enqueued on that CPU as well as tasks which are currently sleeping after an
+ * execution on that CPU.
+ *
+ * This method returns the utilization of the specified CPU by discounting the
+ * utilization of the specified task, whenever the task is currently
+ * contributing to the CPU utilization.
+ */
+unsigned long cpu_util_without(int cpu, struct task_struct *p)
+{
+	/* Task has no contribution or is new */
+	if (cpu != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
+		p = NULL;
 
-		if (env.flags & LBF_NEED_BREAK) {
-			env.flags &= ~LBF_NEED_BREAK;
-			/* Stop if we tried all running tasks */
-			if (env.loop < busiest->nr_running)
-				goto more_balance;
-		}
+	return cpu_util(cpu, p, -1, 0);
+}
 
-		/*
-		 * Revisit (affine) tasks on src_cpu that couldn't be moved to
-		 * us and move them to an alternate dst_cpu in our sched_group
-		 * where they can run. The upper limit on how many times we
-		 * iterate on same src_cpu is dependent on number of CPUs in our
-		 * sched_group.
-		 *
-		 * This changes load balance semantics a bit on who can move
-		 * load to a given_cpu. In addition to the given_cpu itself
-		 * (or a ilb_cpu acting on its behalf where given_cpu is
-		 * nohz-idle), we now have balance_cpu in a position to move
-		 * load to given_cpu. In rare situations, this may cause
-		 * conflicts (balance_cpu and given_cpu/ilb_cpu deciding
-		 * _independently_ and at _same_ time to move some load to
-		 * given_cpu) causing excess load to be moved to given_cpu.
-		 * This however should not happen so much in practice and
-		 * moreover subsequent load balance cycles should correct the
-		 * excess load moved.
-		 */
-		if ((env.flags & LBF_DST_PINNED) && env.imbalance > 0) {
+/*
+ * energy_env - Utilization landscape for energy estimation.
+ * @task_busy_time: Utilization contribution by the task for which we test the
+ *                  placement. Given by eenv_task_busy_time().
+ * @pd_busy_time:   Utilization of the whole perf domain without the task
+ *                  contribution. Given by eenv_pd_busy_time().
+ * @cpu_cap:        Maximum CPU capacity for the perf domain.
+ * @pd_cap:         Entire perf domain capacity. (pd->nr_cpus * cpu_cap).
+ */
+struct energy_env {
+	unsigned long task_busy_time;
+	unsigned long pd_busy_time;
+	unsigned long cpu_cap;
+	unsigned long pd_cap;
+};
 
-			/* Prevent to re-select dst_cpu via env's CPUs */
-			__cpumask_clear_cpu(env.dst_cpu, env.cpus);
+/*
+ * Compute the task busy time for compute_energy(). This time cannot be
+ * injected directly into effective_cpu_util() because of the IRQ scaling.
+ * The latter only makes sense with the most recent CPUs where the task has
+ * run.
+ */
+static inline void eenv_task_busy_time(struct energy_env *eenv,
+				       struct task_struct *p, int prev_cpu)
+{
+	unsigned long busy_time, max_cap = arch_scale_cpu_capacity(prev_cpu);
+	unsigned long irq = cpu_util_irq(cpu_rq(prev_cpu));
 
-			env.dst_rq	 = cpu_rq(env.new_dst_cpu);
-			env.dst_cpu	 = env.new_dst_cpu;
-			env.flags	&= ~LBF_DST_PINNED;
-			env.loop	 = 0;
-			env.loop_break	 = SCHED_NR_MIGRATE_BREAK;
+	if (unlikely(irq >= max_cap))
+		busy_time = max_cap;
+	else
+		busy_time = scale_irq_capacity(task_util_est(p), irq, max_cap);
 
-			/*
-			 * Go back to "more_balance" rather than "redo" since we
-			 * need to continue with same src_cpu.
-			 */
-			goto more_balance;
-		}
+	eenv->task_busy_time = busy_time;
+}
 
-		/*
-		 * We failed to reach balance because of affinity.
-		 */
-		if (sd_parent) {
-			int *group_imbalance = &sd_parent->groups->sgc->imbalance;
+/*
+ * Compute the perf_domain (PD) busy time for compute_energy(). Based on the
+ * utilization for each @pd_cpus, it however doesn't take into account
+ * clamping since the ratio (utilization / cpu_capacity) is already enough to
+ * scale the EM reported power consumption at the (eventually clamped)
+ * cpu_capacity.
+ *
+ * The contribution of the task @p for which we want to estimate the
+ * energy cost is removed (by cpu_util()) and must be calculated
+ * separately (see eenv_task_busy_time). This ensures:
+ *
+ *   - A stable PD utilization, no matter which CPU of that PD we want to place
+ *     the task on.
+ *
+ *   - A fair comparison between CPUs as the task contribution (task_util())
+ *     will always be the same no matter which CPU utilization we rely on
+ *     (util_avg or util_est).
+ *
+ * Set @eenv busy time for the PD that spans @pd_cpus. This busy time can't
+ * exceed @eenv->pd_cap.
+ */
+static inline void eenv_pd_busy_time(struct energy_env *eenv,
+				     struct cpumask *pd_cpus,
+				     struct task_struct *p)
+{
+	unsigned long busy_time = 0;
+	int cpu;
 
-			if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0)
-				*group_imbalance = 1;
-		}
+	for_each_cpu(cpu, pd_cpus) {
+		unsigned long util = cpu_util(cpu, p, -1, 0);
 
-		/* All tasks on this runqueue were pinned by CPU affinity */
-		if (unlikely(env.flags & LBF_ALL_PINNED)) {
-			__cpumask_clear_cpu(cpu_of(busiest), cpus);
-			/*
-			 * Attempting to continue load balancing at the current
-			 * sched_domain level only makes sense if there are
-			 * active CPUs remaining as possible busiest CPUs to
-			 * pull load from which are not contained within the
-			 * destination group that is receiving any migrated
-			 * load.
-			 */
-			if (!cpumask_subset(cpus, env.dst_grpmask)) {
-				env.loop = 0;
-				env.loop_break = SCHED_NR_MIGRATE_BREAK;
-				goto redo;
-			}
-			goto out_all_pinned;
-		}
+		busy_time += effective_cpu_util(cpu, util, NULL, NULL);
 	}
 
-	if (!ld_moved) {
-		schedstat_inc(sd->lb_failed[idle]);
-		/*
-		 * Increment the failure counter only on periodic balance.
-		 * We do not want newidle balance, which can be very
-		 * frequent, pollute the failure counter causing
-		 * excessive cache_hot migrations and active balances.
-		 *
-		 * Similarly for migration_misfit which is not related to
-		 * load/util migration, don't pollute nr_balance_failed.
-		 */
-		if (idle != CPU_NEWLY_IDLE &&
-		    env.migration_type != migrate_misfit)
-			sd->nr_balance_failed++;
+	eenv->pd_busy_time = min(eenv->pd_cap, busy_time);
+}
 
-		if (need_active_balance(&env)) {
-			unsigned long flags;
+/*
+ * Compute the maximum utilization for compute_energy() when the task @p
+ * is placed on the cpu @dst_cpu.
+ *
+ * Returns the maximum utilization among @eenv->cpus. This utilization can't
+ * exceed @eenv->cpu_cap.
+ */
+static inline unsigned long
+eenv_pd_max_util(struct energy_env *eenv, struct cpumask *pd_cpus,
+		 struct task_struct *p, int dst_cpu)
+{
+	unsigned long max_util = 0;
+	int cpu;
 
-			raw_spin_rq_lock_irqsave(busiest, flags);
+	for_each_cpu(cpu, pd_cpus) {
+		struct task_struct *tsk = (cpu == dst_cpu) ? p : NULL;
+		unsigned long util = cpu_util(cpu, p, dst_cpu, 1);
+		unsigned long eff_util, min, max;
 
-			/*
-			 * Don't kick the active_load_balance_cpu_stop,
-			 * if the curr task on busiest CPU can't be
-			 * moved to this_cpu:
-			 */
-			if (!cpumask_test_cpu(this_cpu, busiest->curr->cpus_ptr)) {
-				raw_spin_rq_unlock_irqrestore(busiest, flags);
-				goto out_one_pinned;
-			}
+		/*
+		 * Performance domain frequency: utilization clamping
+		 * must be considered since it affects the selection
+		 * of the performance domain frequency.
+		 * NOTE: in case RT tasks are running, by default the
+		 * FREQUENCY_UTIL's utilization can be max OPP.
+		 */
+		eff_util = effective_cpu_util(cpu, util, &min, &max);
 
-			/* Record that we found at least one task that could run on this_cpu */
-			env.flags &= ~LBF_ALL_PINNED;
+		/* Task's uclamp can modify min and max value */
+		if (tsk && uclamp_is_used()) {
+			min = max(min, uclamp_eff_value(p, UCLAMP_MIN));
 
 			/*
-			 * ->active_balance synchronizes accesses to
-			 * ->active_balance_work.  Once set, it's cleared
-			 * only after active load balance is finished.
+			 * If there is no active max uclamp constraint,
+			 * directly use task's one, otherwise keep max.
 			 */
-			if (!busiest->active_balance) {
-				busiest->active_balance = 1;
-				busiest->push_cpu = this_cpu;
-				active_balance = 1;
-			}
-
-			preempt_disable();
-			raw_spin_rq_unlock_irqrestore(busiest, flags);
-			if (active_balance) {
-				stop_one_cpu_nowait(cpu_of(busiest),
-					active_load_balance_cpu_stop, busiest,
-					&busiest->active_balance_work);
-			}
-			preempt_enable();
+			if (uclamp_rq_is_idle(cpu_rq(cpu)))
+				max = uclamp_eff_value(p, UCLAMP_MAX);
+			else
+				max = max(max, uclamp_eff_value(p, UCLAMP_MAX));
 		}
-	} else {
-		sd->nr_balance_failed = 0;
-	}
-
-	if (likely(!active_balance) || need_active_balance(&env)) {
-		/* We were unbalanced, so reset the balancing interval */
-		sd->balance_interval = sd->min_interval;
-	}
 
-	goto out;
-
-out_balanced:
-	/*
-	 * We reach balance although we may have faced some affinity
-	 * constraints. Clear the imbalance flag only if other tasks got
-	 * a chance to move and fix the imbalance.
-	 */
-	if (sd_parent && !(env.flags & LBF_ALL_PINNED)) {
-		int *group_imbalance = &sd_parent->groups->sgc->imbalance;
-
-		if (*group_imbalance)
-			*group_imbalance = 0;
+		eff_util = sugov_effective_cpu_perf(cpu, eff_util, min, max);
+		max_util = max(max_util, eff_util);
 	}
 
-out_all_pinned:
-	/*
-	 * We reach balance because all tasks are pinned at this level so
-	 * we can't migrate them. Let the imbalance flag set so parent level
-	 * can try to migrate them.
-	 */
-	schedstat_inc(sd->lb_balanced[idle]);
-
-	sd->nr_balance_failed = 0;
-
-out_one_pinned:
-	ld_moved = 0;
-
-	/*
-	 * sched_balance_newidle() disregards balance intervals, so we could
-	 * repeatedly reach this code, which would lead to balance_interval
-	 * skyrocketing in a short amount of time. Skip the balance_interval
-	 * increase logic to avoid that.
-	 *
-	 * Similarly misfit migration which is not necessarily an indication of
-	 * the system being busy and requires lb to backoff to let it settle
-	 * down.
-	 */
-	if (env.idle == CPU_NEWLY_IDLE ||
-	    env.migration_type == migrate_misfit)
-		goto out;
-
-	/* tune up the balancing interval */
-	if ((env.flags & LBF_ALL_PINNED &&
-	     sd->balance_interval < MAX_PINNED_INTERVAL) ||
-	    sd->balance_interval < sd->max_interval)
-		sd->balance_interval *= 2;
-out:
-	return ld_moved;
+	return min(max_util, eenv->cpu_cap);
 }
 
+/*
+ * compute_energy(): Use the Energy Model to estimate the energy that @pd would
+ * consume for a given utilization landscape @eenv. When @dst_cpu < 0, the task
+ * contribution is ignored.
+ */
 static inline unsigned long
-get_sd_balance_interval(struct sched_domain *sd, int cpu_busy)
+compute_energy(struct energy_env *eenv, struct perf_domain *pd,
+	       struct cpumask *pd_cpus, struct task_struct *p, int dst_cpu)
 {
-	unsigned long interval = sd->balance_interval;
-
-	if (cpu_busy)
-		interval *= sd->busy_factor;
-
-	/* scale ms to jiffies */
-	interval = msecs_to_jiffies(interval);
-
-	/*
-	 * Reduce likelihood of busy balancing at higher domains racing with
-	 * balancing at lower domains by preventing their balancing periods
-	 * from being multiples of each other.
-	 */
-	if (cpu_busy)
-		interval -= 1;
-
-	interval = clamp(interval, 1UL, max_load_balance_interval);
+	unsigned long max_util = eenv_pd_max_util(eenv, pd_cpus, p, dst_cpu);
+	unsigned long busy_time = eenv->pd_busy_time;
+	unsigned long energy;
 
-	return interval;
-}
+	if (dst_cpu >= 0)
+		busy_time = min(eenv->pd_cap, busy_time + eenv->task_busy_time);
 
-static inline void
-update_next_balance(struct sched_domain *sd, unsigned long *next_balance)
-{
-	unsigned long interval, next;
+	energy = em_cpu_energy(pd->em_pd, max_util, busy_time, eenv->cpu_cap);
 
-	/* used by idle balance, so cpu_busy = 0 */
-	interval = get_sd_balance_interval(sd, 0);
-	next = sd->last_balance + interval;
+	trace_sched_compute_energy_tp(p, dst_cpu, energy, max_util, busy_time);
 
-	if (time_after(*next_balance, next))
-		*next_balance = next;
+	return energy;
 }
 
 /*
- * active_load_balance_cpu_stop is run by the CPU stopper. It pushes
- * running tasks off the busiest CPU onto idle CPUs. It requires at
- * least 1 task to be running on each physical CPU where possible, and
- * avoids physical / logical imbalances.
+ * find_energy_efficient_cpu(): Find most energy-efficient target CPU for the
+ * waking task. find_energy_efficient_cpu() looks for the CPU with maximum
+ * spare capacity in each performance domain and uses it as a potential
+ * candidate to execute the task. Then, it uses the Energy Model to figure
+ * out which of the CPU candidates is the most energy-efficient.
+ *
+ * The rationale for this heuristic is as follows. In a performance domain,
+ * all the most energy efficient CPU candidates (according to the Energy
+ * Model) are those for which we'll request a low frequency. When there are
+ * several CPUs for which the frequency request will be the same, we don't
+ * have enough data to break the tie between them, because the Energy Model
+ * only includes active power costs. With this model, if we assume that
+ * frequency requests follow utilization (e.g. using schedutil), the CPU with
+ * the maximum spare capacity in a performance domain is guaranteed to be among
+ * the best candidates of the performance domain.
+ *
+ * In practice, it could be preferable from an energy standpoint to pack
+ * small tasks on a CPU in order to let other CPUs go in deeper idle states,
+ * but that could also hurt our chances to go cluster idle, and we have no
+ * ways to tell with the current Energy Model if this is actually a good
+ * idea or not. So, find_energy_efficient_cpu() basically favors
+ * cluster-packing, and spreading inside a cluster. That should at least be
+ * a good thing for latency, and this is consistent with the idea that most
+ * of the energy savings of EAS come from the asymmetry of the system, and
+ * not so much from breaking the tie between identical CPUs. That's also the
+ * reason why EAS is enabled in the topology code only for systems where
+ * SD_ASYM_CPUCAPACITY is set.
+ *
+ * NOTE: Forkees are not accepted in the energy-aware wake-up path because
+ * they don't have any useful utilization data yet and it's not possible to
+ * forecast their impact on energy consumption. Consequently, they will be
+ * placed by sched_balance_find_dst_cpu() on the least loaded CPU, which might turn out
+ * to be energy-inefficient in some use-cases. The alternative would be to
+ * bias new tasks towards specific types of CPUs first, or to try to infer
+ * their util_avg from the parent task, but those heuristics could hurt
+ * other use-cases too. So, until someone finds a better way to solve this,
+ * let's keep things simple by re-using the existing slow path.
  */
-static int active_load_balance_cpu_stop(void *data)
+static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
 {
-	struct rq *busiest_rq = data;
-	int busiest_cpu = cpu_of(busiest_rq);
-	int target_cpu = busiest_rq->push_cpu;
-	struct rq *target_rq = cpu_rq(target_cpu);
+	struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
+	unsigned long prev_delta = ULONG_MAX, best_delta = ULONG_MAX;
+	unsigned long p_util_min = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MIN) : 0;
+	unsigned long p_util_max = uclamp_is_used() ? uclamp_eff_value(p, UCLAMP_MAX) : 1024;
+	struct root_domain *rd = this_rq()->rd;
+	int cpu, best_energy_cpu, target = -1;
+	int prev_fits = -1, best_fits = -1;
+	unsigned long best_thermal_cap = 0;
+	unsigned long prev_thermal_cap = 0;
 	struct sched_domain *sd;
-	struct task_struct *p = NULL;
-	struct rq_flags rf;
+	struct perf_domain *pd;
+	struct energy_env eenv;
+
+	rcu_read_lock();
+	pd = rcu_dereference(rd->pd);
+	if (!pd)
+		goto unlock;
 
-	rq_lock_irq(busiest_rq, &rf);
 	/*
-	 * Between queueing the stop-work and running it is a hole in which
-	 * CPUs can become inactive. We should not move tasks from or to
-	 * inactive CPUs.
+	 * Energy-aware wake-up happens on the lowest sched_domain starting
+	 * from sd_asym_cpucapacity spanning over this_cpu and prev_cpu.
 	 */
-	if (!cpu_active(busiest_cpu) || !cpu_active(target_cpu))
-		goto out_unlock;
+	sd = rcu_dereference(*this_cpu_ptr(&sd_asym_cpucapacity));
+	while (sd && !cpumask_test_cpu(prev_cpu, sched_domain_span(sd)))
+		sd = sd->parent;
+	if (!sd)
+		goto unlock;
 
-	/* Make sure the requested CPU hasn't gone down in the meantime: */
-	if (unlikely(busiest_cpu != smp_processor_id() ||
-		     !busiest_rq->active_balance))
-		goto out_unlock;
+	target = prev_cpu;
 
-	/* Is there any task to move? */
-	if (busiest_rq->nr_running <= 1)
-		goto out_unlock;
+	sync_entity_load_avg(&p->se);
+	if (!task_util_est(p) && p_util_min == 0)
+		goto unlock;
 
-	/*
-	 * This condition is "impossible", if it occurs
-	 * we need to fix it. Originally reported by
-	 * Bjorn Helgaas on a 128-CPU setup.
-	 */
-	WARN_ON_ONCE(busiest_rq == target_rq);
+	eenv_task_busy_time(&eenv, p, prev_cpu);
 
-	/* Search for an sd spanning us and the target CPU. */
-	rcu_read_lock();
-	for_each_domain(target_cpu, sd) {
-		if (cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
-			break;
-	}
+	for (; pd; pd = pd->next) {
+		unsigned long util_min = p_util_min, util_max = p_util_max;
+		unsigned long cpu_cap, cpu_thermal_cap, util;
+		long prev_spare_cap = -1, max_spare_cap = -1;
+		unsigned long rq_util_min, rq_util_max;
+		unsigned long cur_delta, base_energy;
+		int max_spare_cap_cpu = -1;
+		int fits, max_fits = -1;
 
-	if (likely(sd)) {
-		struct lb_env env = {
-			.sd		= sd,
-			.dst_cpu	= target_cpu,
-			.dst_rq		= target_rq,
-			.src_cpu	= busiest_rq->cpu,
-			.src_rq		= busiest_rq,
-			.idle		= CPU_IDLE,
-			.flags		= LBF_ACTIVE_LB,
-		};
-
-		schedstat_inc(sd->alb_count);
-		update_rq_clock(busiest_rq);
-
-		p = detach_one_task(&env);
-		if (p) {
-			schedstat_inc(sd->alb_pushed);
-			/* Active balancing done, reset the failure counter. */
-			sd->nr_balance_failed = 0;
-		} else {
-			schedstat_inc(sd->alb_failed);
-		}
-	}
-	rcu_read_unlock();
-out_unlock:
-	busiest_rq->active_balance = 0;
-	rq_unlock(busiest_rq, &rf);
+		cpumask_and(cpus, perf_domain_span(pd), cpu_online_mask);
 
-	if (p)
-		attach_one_task(target_rq, p);
+		if (cpumask_empty(cpus))
+			continue;
 
-	local_irq_enable();
+		/* Account thermal pressure for the energy estimation */
+		cpu = cpumask_first(cpus);
+		cpu_thermal_cap = arch_scale_cpu_capacity(cpu);
+		cpu_thermal_cap -= arch_scale_thermal_pressure(cpu);
 
-	return 0;
-}
+		eenv.cpu_cap = cpu_thermal_cap;
+		eenv.pd_cap = 0;
 
-/*
- * This flag serializes load-balancing passes over large domains
- * (above the NODE topology level) - only one load-balancing instance
- * may run at a time, to reduce overhead on very large systems with
- * lots of CPUs and large NUMA distances.
- *
- * - Note that load-balancing passes triggered while another one
- *   is executing are skipped and not re-tried.
- *
- * - Also note that this does not serialize rebalance_domains()
- *   execution, as non-SD_SERIALIZE domains will still be
- *   load-balanced in parallel.
- */
-static atomic_t sched_balance_running = ATOMIC_INIT(0);
+		for_each_cpu(cpu, cpus) {
+			struct rq *rq = cpu_rq(cpu);
 
-/*
- * Scale the max sched_balance_rq interval with the number of CPUs in the system.
- * This trades load-balance latency on larger machines for less cross talk.
- */
-void update_max_interval(void)
-{
-	max_load_balance_interval = HZ*num_online_cpus()/10;
-}
+			eenv.pd_cap += cpu_thermal_cap;
 
-static inline bool update_newidle_cost(struct sched_domain *sd, u64 cost)
-{
-	if (cost > sd->max_newidle_lb_cost) {
-		/*
-		 * Track max cost of a domain to make sure to not delay the
-		 * next wakeup on the CPU.
-		 */
-		sd->max_newidle_lb_cost = cost;
-		sd->last_decay_max_lb_cost = jiffies;
-	} else if (time_after(jiffies, sd->last_decay_max_lb_cost + HZ)) {
-		/*
-		 * Decay the newidle max times by ~1% per second to ensure that
-		 * it is not outdated and the current max cost is actually
-		 * shorter.
-		 */
-		sd->max_newidle_lb_cost = (sd->max_newidle_lb_cost * 253) / 256;
-		sd->last_decay_max_lb_cost = jiffies;
+			if (!cpumask_test_cpu(cpu, sched_domain_span(sd)))
+				continue;
 
-		return true;
-	}
+			if (!cpumask_test_cpu(cpu, p->cpus_ptr))
+				continue;
 
-	return false;
-}
+			util = cpu_util(cpu, p, cpu, 0);
+			cpu_cap = capacity_of(cpu);
 
-/*
- * It checks each scheduling domain to see if it is due to be balanced,
- * and initiates a balancing operation if so.
- *
- * Balancing parameters are set up in init_sched_domains.
- */
-static void sched_balance_domains(struct rq *rq, enum cpu_idle_type idle)
-{
-	int continue_balancing = 1;
-	int cpu = rq->cpu;
-	int busy = idle != CPU_IDLE && !sched_idle_cpu(cpu);
-	unsigned long interval;
-	struct sched_domain *sd;
-	/* Earliest time when we have to do rebalance again */
-	unsigned long next_balance = jiffies + 60*HZ;
-	int update_next_balance = 0;
-	int need_serialize, need_decay = 0;
-	u64 max_cost = 0;
+			/*
+			 * Skip CPUs that cannot satisfy the capacity request.
+			 * IOW, placing the task there would make the CPU
+			 * overutilized. Take uclamp into account to see how
+			 * much capacity we can get out of the CPU; this is
+			 * aligned with sched_cpu_util().
+			 */
+			if (uclamp_is_used() && !uclamp_rq_is_idle(rq)) {
+				/*
+				 * Open code uclamp_rq_util_with() except for
+				 * the clamp() part. I.e.: apply max aggregation
+				 * only. util_fits_cpu() logic requires to
+				 * operate on non clamped util but must use the
+				 * max-aggregated uclamp_{min, max}.
+				 */
+				rq_util_min = uclamp_rq_get(rq, UCLAMP_MIN);
+				rq_util_max = uclamp_rq_get(rq, UCLAMP_MAX);
 
-	rcu_read_lock();
-	for_each_domain(cpu, sd) {
-		/*
-		 * Decay the newidle max times here because this is a regular
-		 * visit to all the domains.
-		 */
-		need_decay = update_newidle_cost(sd, 0);
-		max_cost += sd->max_newidle_lb_cost;
+				util_min = max(rq_util_min, p_util_min);
+				util_max = max(rq_util_max, p_util_max);
+			}
 
-		/*
-		 * Stop the load balance at this level. There is another
-		 * CPU in our sched group which is doing load balancing more
-		 * actively.
-		 */
-		if (!continue_balancing) {
-			if (need_decay)
+			fits = util_fits_cpu(util, util_min, util_max, cpu);
+			if (!fits)
 				continue;
-			break;
-		}
 
-		interval = get_sd_balance_interval(sd, busy);
-
-		need_serialize = sd->flags & SD_SERIALIZE;
-		if (need_serialize) {
-			if (atomic_cmpxchg_acquire(&sched_balance_running, 0, 1))
-				goto out;
-		}
+			lsub_positive(&cpu_cap, util);
 
-		if (time_after_eq(jiffies, sd->last_balance + interval)) {
-			if (sched_balance_rq(cpu, rq, sd, idle, &continue_balancing)) {
+			if (cpu == prev_cpu) {
+				/* Always use prev_cpu as a candidate. */
+				prev_spare_cap = cpu_cap;
+				prev_fits = fits;
+			} else if ((fits > max_fits) ||
+				   ((fits == max_fits) && ((long)cpu_cap > max_spare_cap))) {
 				/*
-				 * The LBF_DST_PINNED logic could have changed
-				 * env->dst_cpu, so we can't know our idle
-				 * state even if we migrated tasks. Update it.
+				 * Find the CPU with the maximum spare capacity
+				 * among the remaining CPUs in the performance
+				 * domain.
 				 */
-				idle = idle_cpu(cpu);
-				busy = !idle && !sched_idle_cpu(cpu);
+				max_spare_cap = cpu_cap;
+				max_spare_cap_cpu = cpu;
+				max_fits = fits;
 			}
-			sd->last_balance = jiffies;
-			interval = get_sd_balance_interval(sd, busy);
 		}
-		if (need_serialize)
-			atomic_set_release(&sched_balance_running, 0);
-out:
-		if (time_after(next_balance, sd->last_balance + interval)) {
-			next_balance = sd->last_balance + interval;
-			update_next_balance = 1;
-		}
-	}
-	if (need_decay) {
-		/*
-		 * Ensure the rq-wide value also decays but keep it at a
-		 * reasonable floor to avoid funnies with rq->avg_idle.
-		 */
-		rq->max_idle_balance_cost =
-			max((u64)sysctl_sched_migration_cost, max_cost);
-	}
-	rcu_read_unlock();
 
-	/*
-	 * next_balance will be updated only when there is a need.
-	 * When the cpu is attached to null domain for ex, it will not be
-	 * updated.
-	 */
-	if (likely(update_next_balance))
-		rq->next_balance = next_balance;
+		if (max_spare_cap_cpu < 0 && prev_spare_cap < 0)
+			continue;
 
-}
+		eenv_pd_busy_time(&eenv, cpus, p);
+		/* Compute the 'base' energy of the pd, without @p */
+		base_energy = compute_energy(&eenv, pd, cpus, p, -1);
 
-static inline int on_null_domain(struct rq *rq)
-{
-	return unlikely(!rcu_dereference_sched(rq->sd));
-}
+		/* Evaluate the energy impact of using prev_cpu. */
+		if (prev_spare_cap > -1) {
+			prev_delta = compute_energy(&eenv, pd, cpus, p,
+						    prev_cpu);
+			/* CPU utilization has changed */
+			if (prev_delta < base_energy)
+				goto unlock;
+			prev_delta -= base_energy;
+			prev_thermal_cap = cpu_thermal_cap;
+			best_delta = min(best_delta, prev_delta);
+		}
 
-#ifdef CONFIG_NO_HZ_COMMON
-/*
- * NOHZ idle load balancing (ILB) details:
- *
- * - When one of the busy CPUs notices that there may be an idle rebalancing
- *   needed, they will kick the idle load balancer, which then does idle
- *   load balancing for all the idle CPUs.
- *
- * - HK_TYPE_MISC CPUs are used for this task, because HK_TYPE_SCHED is not set
- *   anywhere yet.
- */
-static inline int find_new_ilb(void)
-{
-	const struct cpumask *hk_mask;
-	int ilb_cpu;
+		/* Evaluate the energy impact of using max_spare_cap_cpu. */
+		if (max_spare_cap_cpu >= 0 && max_spare_cap > prev_spare_cap) {
+			/* Current best energy cpu fits better */
+			if (max_fits < best_fits)
+				continue;
 
-	hk_mask = housekeeping_cpumask(HK_TYPE_MISC);
+			/*
+			 * Both don't fit performance hint (i.e. uclamp_min)
+			 * but best energy cpu has better capacity.
+			 */
+			if ((max_fits < 0) &&
+			    (cpu_thermal_cap <= best_thermal_cap))
+				continue;
 
-	for_each_cpu_and(ilb_cpu, nohz.idle_cpus_mask, hk_mask) {
+			cur_delta = compute_energy(&eenv, pd, cpus, p,
+						   max_spare_cap_cpu);
+			/* CPU utilization has changed */
+			if (cur_delta < base_energy)
+				goto unlock;
+			cur_delta -= base_energy;
 
-		if (ilb_cpu == smp_processor_id())
-			continue;
+			/*
+			 * Both fit for the task but best energy cpu has lower
+			 * energy impact.
+			 */
+			if ((max_fits > 0) && (best_fits > 0) &&
+			    (cur_delta >= best_delta))
+				continue;
 
-		if (idle_cpu(ilb_cpu))
-			return ilb_cpu;
+			best_delta = cur_delta;
+			best_energy_cpu = max_spare_cap_cpu;
+			best_fits = max_fits;
+			best_thermal_cap = cpu_thermal_cap;
+		}
 	}
+	rcu_read_unlock();
 
-	return -1;
-}
-
-/*
- * Kick a CPU to do the NOHZ balancing, if it is time for it, via a cross-CPU
- * SMP function call (IPI).
- *
- * We pick the first idle CPU in the HK_TYPE_MISC housekeeping set (if there is one).
- */
-static void kick_ilb(unsigned int flags)
-{
-	int ilb_cpu;
-
-	/*
-	 * Increase nohz.next_balance only when if full ilb is triggered but
-	 * not if we only update stats.
-	 */
-	if (flags & NOHZ_BALANCE_KICK)
-		nohz.next_balance = jiffies+1;
+	if ((best_fits > prev_fits) ||
+	    ((best_fits > 0) && (best_delta < prev_delta)) ||
+	    ((best_fits < 0) && (best_thermal_cap > prev_thermal_cap)))
+		target = best_energy_cpu;
 
-	ilb_cpu = find_new_ilb();
-	if (ilb_cpu < 0)
-		return;
+	return target;
 
-	/*
-	 * Access to rq::nohz_csd is serialized by NOHZ_KICK_MASK; he who sets
-	 * the first flag owns it; cleared by nohz_csd_func().
-	 */
-	flags = atomic_fetch_or(flags, nohz_flags(ilb_cpu));
-	if (flags & NOHZ_KICK_MASK)
-		return;
+unlock:
+	rcu_read_unlock();
 
-	/*
-	 * This way we generate an IPI on the target CPU which
-	 * is idle, and the softirq performing NOHZ idle load balancing
-	 * will be run before returning from the IPI.
-	 */
-	smp_call_function_single_async(ilb_cpu, &cpu_rq(ilb_cpu)->nohz_csd);
+	return target;
 }
 
 /*
- * Current decision point for kicking the idle load balancer in the presence
- * of idle CPUs in the system.
+ * select_task_rq_fair: Select target runqueue for the waking task in domains
+ * that have the relevant SD flag set. In practice, this is SD_BALANCE_WAKE,
+ * SD_BALANCE_FORK, or SD_BALANCE_EXEC.
+ *
+ * Balances load by selecting the idlest CPU in the idlest group, or under
+ * certain conditions an idle sibling CPU if the domain has SD_WAKE_AFFINE set.
+ *
+ * Returns the target CPU number.
  */
-static void nohz_balancer_kick(struct rq *rq)
+static int
+select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags)
 {
-	unsigned long now = jiffies;
-	struct sched_domain_shared *sds;
-	struct sched_domain *sd;
-	int nr_busy, i, cpu = rq->cpu;
-	unsigned int flags = 0;
-
-	if (unlikely(rq->idle_balance))
-		return;
-
-	/*
-	 * We may be recently in ticked or tickless idle mode. At the first
-	 * busy tick after returning from idle, we will update the busy stats.
-	 */
-	nohz_balance_exit_idle(rq);
+	int sync = (wake_flags & WF_SYNC) && !(current->flags & PF_EXITING);
+	struct sched_domain *tmp, *sd = NULL;
+	int cpu = smp_processor_id();
+	int new_cpu = prev_cpu;
+	int want_affine = 0;
+	/* SD_flags and WF_flags share the first nibble */
+	int sd_flag = wake_flags & 0xF;
 
 	/*
-	 * None are in tickless mode and hence no need for NOHZ idle load
-	 * balancing:
+	 * required for stable ->cpus_allowed
 	 */
-	if (likely(!atomic_read(&nohz.nr_cpus)))
-		return;
+	lockdep_assert_held(&p->pi_lock);
+	if (wake_flags & WF_TTWU) {
+		record_wakee(p);
 
-	if (READ_ONCE(nohz.has_blocked) &&
-	    time_after(now, READ_ONCE(nohz.next_blocked)))
-		flags = NOHZ_STATS_KICK;
+		if ((wake_flags & WF_CURRENT_CPU) &&
+		    cpumask_test_cpu(cpu, p->cpus_ptr))
+			return cpu;
 
-	if (time_before(now, nohz.next_balance))
-		goto out;
+		if (!is_rd_overutilized(this_rq()->rd)) {
+			new_cpu = find_energy_efficient_cpu(p, prev_cpu);
+			if (new_cpu >= 0)
+				return new_cpu;
+			new_cpu = prev_cpu;
+		}
 
-	if (rq->nr_running >= 2) {
-		flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
-		goto out;
+		want_affine = !wake_wide(p) && cpumask_test_cpu(cpu, p->cpus_ptr);
 	}
 
 	rcu_read_lock();
-
-	sd = rcu_dereference(rq->sd);
-	if (sd) {
-		/*
-		 * If there's a runnable CFS task and the current CPU has reduced
-		 * capacity, kick the ILB to see if there's a better CPU to run on:
-		 */
-		if (rq->cfs.h_nr_running >= 1 && check_cpu_capacity(rq, sd)) {
-			flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
-			goto unlock;
-		}
-	}
-
-	sd = rcu_dereference(per_cpu(sd_asym_packing, cpu));
-	if (sd) {
+	for_each_domain(cpu, tmp) {
 		/*
-		 * When ASYM_PACKING; see if there's a more preferred CPU
-		 * currently idle; in which case, kick the ILB to move tasks
-		 * around.
-		 *
-		 * When balancing between cores, all the SMT siblings of the
-		 * preferred CPU must be idle.
+		 * If both 'cpu' and 'prev_cpu' are part of this domain,
+		 * cpu is a valid SD_WAKE_AFFINE target.
 		 */
-		for_each_cpu_and(i, sched_domain_span(sd), nohz.idle_cpus_mask) {
-			if (sched_asym(sd, i, cpu)) {
-				flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
-				goto unlock;
-			}
-		}
-	}
+		if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
+		    cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
+			if (cpu != prev_cpu)
+				new_cpu = wake_affine(tmp, p, cpu, prev_cpu, sync);
 
-	sd = rcu_dereference(per_cpu(sd_asym_cpucapacity, cpu));
-	if (sd) {
-		/*
-		 * When ASYM_CPUCAPACITY; see if there's a higher capacity CPU
-		 * to run the misfit task on.
-		 */
-		if (check_misfit_status(rq)) {
-			flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
-			goto unlock;
+			sd = NULL; /* Prefer wake_affine over balance flags */
+			break;
 		}
 
 		/*
-		 * For asymmetric systems, we do not want to nicely balance
-		 * cache use, instead we want to embrace asymmetry and only
-		 * ensure tasks have enough CPU capacity.
-		 *
-		 * Skip the LLC logic because it's not relevant in that case.
+		 * Usually only true for WF_EXEC and WF_FORK, as sched_domains
+		 * usually do not have SD_BALANCE_WAKE set. That means wakeup
+		 * will usually go to the fast path.
 		 */
-		goto unlock;
+		if (tmp->flags & sd_flag)
+			sd = tmp;
+		else if (!want_affine)
+			break;
 	}
 
-	sds = rcu_dereference(per_cpu(sd_llc_shared, cpu));
-	if (sds) {
-		/*
-		 * If there is an imbalance between LLC domains (IOW we could
-		 * increase the overall cache utilization), we need a less-loaded LLC
-		 * domain to pull some load from. Likewise, we may need to spread
-		 * load within the current LLC domain (e.g. packed SMT cores but
-		 * other CPUs are idle). We can't really know from here how busy
-		 * the others are - so just get a NOHZ balance going if it looks
-		 * like this LLC domain has tasks we could move.
-		 */
-		nr_busy = atomic_read(&sds->nr_busy_cpus);
-		if (nr_busy > 1) {
-			flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
-			goto unlock;
-		}
+	if (unlikely(sd)) {
+		/* Slow path */
+		new_cpu = sched_balance_find_dst_cpu(sd, p, cpu, prev_cpu, sd_flag);
+	} else if (wake_flags & WF_TTWU) { /* XXX always ? */
+		/* Fast path */
+		new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);
 	}
-unlock:
 	rcu_read_unlock();
-out:
-	if (READ_ONCE(nohz.needs_update))
-		flags |= NOHZ_NEXT_KICK;
 
-	if (flags)
-		kick_ilb(flags);
+	return new_cpu;
 }
 
-static void set_cpu_sd_state_busy(int cpu)
+/*
+ * Called immediately before a task is migrated to a new CPU; task_cpu(p) and
+ * cfs_rq_of(p) references at time of call are still valid and identify the
+ * previous CPU. The caller guarantees p->pi_lock or task_rq(p)->lock is held.
+ */
+static void migrate_task_rq_fair(struct task_struct *p, int new_cpu)
 {
-	struct sched_domain *sd;
-
-	rcu_read_lock();
-	sd = rcu_dereference(per_cpu(sd_llc, cpu));
-
-	if (!sd || !sd->nohz_idle)
-		goto unlock;
-	sd->nohz_idle = 0;
-
-	atomic_inc(&sd->shared->nr_busy_cpus);
-unlock:
-	rcu_read_unlock();
-}
+	struct sched_entity *se = &p->se;
 
-void nohz_balance_exit_idle(struct rq *rq)
-{
-	SCHED_WARN_ON(rq != this_rq());
+	if (!task_on_rq_migrating(p)) {
+		remove_entity_load_avg(se);
 
-	if (likely(!rq->nohz_tick_stopped))
-		return;
+		/*
+		 * Here, the task's PELT values have been updated according to
+		 * the current rq's clock. But if that clock hasn't been
+		 * updated in a while, a substantial idle time will be missed,
+		 * leading to an inflation after wake-up on the new rq.
+		 *
+		 * Estimate the missing time from the cfs_rq last_update_time
+		 * and update sched_avg to improve the PELT continuity after
+		 * migration.
+		 */
+		migrate_se_pelt_lag(se);
+	}
 
-	rq->nohz_tick_stopped = 0;
-	cpumask_clear_cpu(rq->cpu, nohz.idle_cpus_mask);
-	atomic_dec(&nohz.nr_cpus);
+	/* Tell new CPU we are migrated */
+	se->avg.last_update_time = 0;
 
-	set_cpu_sd_state_busy(rq->cpu);
+	update_scan_period(p, new_cpu);
 }
 
-static void set_cpu_sd_state_idle(int cpu)
+static void task_dead_fair(struct task_struct *p)
 {
-	struct sched_domain *sd;
-
-	rcu_read_lock();
-	sd = rcu_dereference(per_cpu(sd_llc, cpu));
-
-	if (!sd || sd->nohz_idle)
-		goto unlock;
-	sd->nohz_idle = 1;
-
-	atomic_dec(&sd->shared->nr_busy_cpus);
-unlock:
-	rcu_read_unlock();
+	remove_entity_load_avg(&p->se);
 }
 
 /*
- * This routine will record that the CPU is going idle with tick stopped.
- * This info will be used in performing idle load balancing in the future.
+ * Set the max capacity the task is allowed to run at for misfit detection.
  */
-void nohz_balance_enter_idle(int cpu)
+static void set_task_max_allowed_capacity(struct task_struct *p)
 {
-	struct rq *rq = cpu_rq(cpu);
-
-	SCHED_WARN_ON(cpu != smp_processor_id());
-
-	/* If this CPU is going down, then nothing needs to be done: */
-	if (!cpu_active(cpu))
-		return;
-
-	/* Spare idle load balancing on CPUs that don't want to be disturbed: */
-	if (!housekeeping_cpu(cpu, HK_TYPE_SCHED))
-		return;
-
-	/*
-	 * Can be set safely without rq->lock held
-	 * If a clear happens, it will have evaluated last additions because
-	 * rq->lock is held during the check and the clear
-	 */
-	rq->has_blocked_load = 1;
-
-	/*
-	 * The tick is still stopped but load could have been added in the
-	 * meantime. We set the nohz.has_blocked flag to trig a check of the
-	 * *_avg. The CPU is already part of nohz.idle_cpus_mask so the clear
-	 * of nohz.has_blocked can only happen after checking the new load
-	 */
-	if (rq->nohz_tick_stopped)
-		goto out;
+	struct asym_cap_data *entry;
 
-	/* If we're a completely isolated CPU, we don't play: */
-	if (on_null_domain(rq))
+	if (!sched_asym_cpucap_active())
 		return;
 
-	rq->nohz_tick_stopped = 1;
-
-	cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
-	atomic_inc(&nohz.nr_cpus);
-
-	/*
-	 * Ensures that if nohz_idle_balance() fails to observe our
-	 * @idle_cpus_mask store, it must observe the @has_blocked
-	 * and @needs_update stores.
-	 */
-	smp_mb__after_atomic();
+	rcu_read_lock();
+	list_for_each_entry_rcu(entry, &asym_cap_list, link) {
+		cpumask_t *cpumask;
 
-	set_cpu_sd_state_idle(cpu);
+		cpumask = cpu_capacity_span(entry);
+		if (!cpumask_intersects(p->cpus_ptr, cpumask))
+			continue;
 
-	WRITE_ONCE(nohz.needs_update, 1);
-out:
-	/*
-	 * Each time a cpu enter idle, we assume that it has blocked load and
-	 * enable the periodic update of the load of idle CPUs
-	 */
-	WRITE_ONCE(nohz.has_blocked, 1);
+		p->max_allowed_capacity = entry->capacity;
+		break;
+	}
+	rcu_read_unlock();
 }
 
-static bool update_nohz_stats(struct rq *rq)
+static void set_cpus_allowed_fair(struct task_struct *p, struct affinity_context *ctx)
 {
-	unsigned int cpu = rq->cpu;
-
-	if (!rq->has_blocked_load)
-		return false;
-
-	if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))
-		return false;
+	set_cpus_allowed_common(p, ctx);
+	set_task_max_allowed_capacity(p);
+}
 
-	if (!time_after(jiffies, READ_ONCE(rq->last_blocked_load_update_tick)))
-		return true;
+static int
+balance_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
+{
+	if (rq->nr_running)
+		return 1;
 
-	sched_balance_update_blocked_averages(cpu);
+	return sched_balance_newidle(rq, rf) != 0;
+}
+#else
+static inline void set_task_max_allowed_capacity(struct task_struct *p) {}
+#endif /* CONFIG_SMP */
 
-	return rq->has_blocked_load;
+static void set_next_buddy(struct sched_entity *se)
+{
+	for_each_sched_entity(se) {
+		if (SCHED_WARN_ON(!se->on_rq))
+			return;
+		if (se_is_idle(se))
+			return;
+		cfs_rq_of(se)->next = se;
+	}
 }
 
 /*
- * Internal function that runs load balance for all idle CPUs. The load balance
- * can be a simple update of blocked load or a complete load balance with
- * tasks movement depending of flags.
+ * Preempt the current task with a newly woken task if needed:
  */
-static void _nohz_idle_balance(struct rq *this_rq, unsigned int flags)
-{
-	/* Earliest time when we have to do rebalance again */
-	unsigned long now = jiffies;
-	unsigned long next_balance = now + 60*HZ;
-	bool has_blocked_load = false;
-	int update_next_balance = 0;
-	int this_cpu = this_rq->cpu;
-	int balance_cpu;
-	struct rq *rq;
+static void check_preempt_wakeup_fair(struct rq *rq, struct task_struct *p, int wake_flags)
+{
+	struct task_struct *curr = rq->curr;
+	struct sched_entity *se = &curr->se, *pse = &p->se;
+	struct cfs_rq *cfs_rq = task_cfs_rq(curr);
+	int cse_is_idle, pse_is_idle;
 
-	SCHED_WARN_ON((flags & NOHZ_KICK_MASK) == NOHZ_BALANCE_KICK);
+	if (unlikely(se == pse))
+		return;
 
 	/*
-	 * We assume there will be no idle load after this update and clear
-	 * the has_blocked flag. If a cpu enters idle in the mean time, it will
-	 * set the has_blocked flag and trigger another update of idle load.
-	 * Because a cpu that becomes idle, is added to idle_cpus_mask before
-	 * setting the flag, we are sure to not clear the state and not
-	 * check the load of an idle cpu.
-	 *
-	 * Same applies to idle_cpus_mask vs needs_update.
+	 * This is possible from callers such as attach_tasks(), in which we
+	 * unconditionally wakeup_preempt() after an enqueue (which may have
+	 * lead to a throttle).  This both saves work and prevents false
+	 * next-buddy nomination below.
 	 */
-	if (flags & NOHZ_STATS_KICK)
-		WRITE_ONCE(nohz.has_blocked, 0);
-	if (flags & NOHZ_NEXT_KICK)
-		WRITE_ONCE(nohz.needs_update, 0);
+	if (unlikely(throttled_hierarchy(cfs_rq_of(pse))))
+		return;
 
-	/*
-	 * Ensures that if we miss the CPU, we must see the has_blocked
-	 * store from nohz_balance_enter_idle().
-	 */
-	smp_mb();
+	if (sched_feat(NEXT_BUDDY) && !(wake_flags & WF_FORK)) {
+		set_next_buddy(pse);
+	}
 
 	/*
-	 * Start with the next CPU after this_cpu so we will end with this_cpu and let a
-	 * chance for other idle cpu to pull load.
+	 * We can come here with TIF_NEED_RESCHED already set from new task
+	 * wake up path.
+	 *
+	 * Note: this also catches the edge-case of curr being in a throttled
+	 * group (e.g. via set_curr_task), since update_curr() (in the
+	 * enqueue of curr) will have resulted in resched being set.  This
+	 * prevents us from potentially nominating it as a false LAST_BUDDY
+	 * below.
 	 */
-	for_each_cpu_wrap(balance_cpu,  nohz.idle_cpus_mask, this_cpu+1) {
-		if (!idle_cpu(balance_cpu))
-			continue;
-
-		/*
-		 * If this CPU gets work to do, stop the load balancing
-		 * work being done for other CPUs. Next load
-		 * balancing owner will pick it up.
-		 */
-		if (need_resched()) {
-			if (flags & NOHZ_STATS_KICK)
-				has_blocked_load = true;
-			if (flags & NOHZ_NEXT_KICK)
-				WRITE_ONCE(nohz.needs_update, 1);
-			goto abort;
-		}
+	if (test_tsk_need_resched(curr))
+		return;
 
-		rq = cpu_rq(balance_cpu);
+	/* Idle tasks are by definition preempted by non-idle tasks. */
+	if (unlikely(task_has_idle_policy(curr)) &&
+	    likely(!task_has_idle_policy(p)))
+		goto preempt;
 
-		if (flags & NOHZ_STATS_KICK)
-			has_blocked_load |= update_nohz_stats(rq);
+	/*
+	 * Batch and idle tasks do not preempt non-idle tasks (their preemption
+	 * is driven by the tick):
+	 */
+	if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION))
+		return;
 
-		/*
-		 * If time for next balance is due,
-		 * do the balance.
-		 */
-		if (time_after_eq(jiffies, rq->next_balance)) {
-			struct rq_flags rf;
+	find_matching_se(&se, &pse);
+	WARN_ON_ONCE(!pse);
 
-			rq_lock_irqsave(rq, &rf);
-			update_rq_clock(rq);
-			rq_unlock_irqrestore(rq, &rf);
+	cse_is_idle = se_is_idle(se);
+	pse_is_idle = se_is_idle(pse);
 
-			if (flags & NOHZ_BALANCE_KICK)
-				sched_balance_domains(rq, CPU_IDLE);
-		}
+	/*
+	 * Preempt an idle group in favor of a non-idle group (and don't preempt
+	 * in the inverse case).
+	 */
+	if (cse_is_idle && !pse_is_idle)
+		goto preempt;
+	if (cse_is_idle != pse_is_idle)
+		return;
 
-		if (time_after(next_balance, rq->next_balance)) {
-			next_balance = rq->next_balance;
-			update_next_balance = 1;
-		}
-	}
+	cfs_rq = cfs_rq_of(se);
+	update_curr(cfs_rq);
 
 	/*
-	 * next_balance will be updated only when there is a need.
-	 * When the CPU is attached to null domain for ex, it will not be
-	 * updated.
+	 * XXX pick_eevdf(cfs_rq) != se ?
 	 */
-	if (likely(update_next_balance))
-		nohz.next_balance = next_balance;
+	if (pick_eevdf(cfs_rq) == pse)
+		goto preempt;
 
-	if (flags & NOHZ_STATS_KICK)
-		WRITE_ONCE(nohz.next_blocked,
-			   now + msecs_to_jiffies(LOAD_AVG_PERIOD));
+	return;
 
-abort:
-	/* There is still blocked load, enable periodic update */
-	if (has_blocked_load)
-		WRITE_ONCE(nohz.has_blocked, 1);
+preempt:
+	resched_curr(rq);
 }
 
-/*
- * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the
- * rebalancing for all the CPUs for whom scheduler ticks are stopped.
- */
-static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
+#ifdef CONFIG_SMP
+static struct task_struct *pick_task_fair(struct rq *rq)
 {
-	unsigned int flags = this_rq->nohz_idle_balance;
-
-	if (!flags)
-		return false;
-
-	this_rq->nohz_idle_balance = 0;
+	struct sched_entity *se;
+	struct cfs_rq *cfs_rq;
 
-	if (idle != CPU_IDLE)
-		return false;
+again:
+	cfs_rq = &rq->cfs;
+	if (!cfs_rq->nr_running)
+		return NULL;
 
-	_nohz_idle_balance(this_rq, flags);
+	do {
+		struct sched_entity *curr = cfs_rq->curr;
 
-	return true;
-}
+		/* When we pick for a remote RQ, we'll not have done put_prev_entity() */
+		if (curr) {
+			if (curr->on_rq)
+				update_curr(cfs_rq);
+			else
+				curr = NULL;
 
-/*
- * Check if we need to directly run the ILB for updating blocked load before
- * entering idle state. Here we run ILB directly without issuing IPIs.
- *
- * Note that when this function is called, the tick may not yet be stopped on
- * this CPU yet. nohz.idle_cpus_mask is updated only when tick is stopped and
- * cleared on the next busy tick. In other words, nohz.idle_cpus_mask updates
- * don't align with CPUs enter/exit idle to avoid bottlenecks due to high idle
- * entry/exit rate (usec). So it is possible that _nohz_idle_balance() is
- * called from this function on (this) CPU that's not yet in the mask. That's
- * OK because the goal of nohz_run_idle_balance() is to run ILB only for
- * updating the blocked load of already idle CPUs without waking up one of
- * those idle CPUs and outside the preempt disable / IRQ off phase of the local
- * cpu about to enter idle, because it can take a long time.
- */
-void nohz_run_idle_balance(int cpu)
-{
-	unsigned int flags;
+			if (unlikely(check_cfs_rq_runtime(cfs_rq)))
+				goto again;
+		}
 
-	flags = atomic_fetch_andnot(NOHZ_NEWILB_KICK, nohz_flags(cpu));
+		se = pick_next_entity(cfs_rq);
+		cfs_rq = group_cfs_rq(se);
+	} while (cfs_rq);
 
-	/*
-	 * Update the blocked load only if no SCHED_SOFTIRQ is about to happen
-	 * (i.e. NOHZ_STATS_KICK set) and will do the same.
-	 */
-	if ((flags == NOHZ_NEWILB_KICK) && !need_resched())
-		_nohz_idle_balance(cpu_rq(cpu), NOHZ_STATS_KICK);
+	return task_of(se);
 }
+#endif
 
-static void nohz_newidle_balance(struct rq *this_rq)
+struct task_struct *
+pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 {
-	int this_cpu = this_rq->cpu;
-
-	/*
-	 * This CPU doesn't want to be disturbed by scheduler
-	 * housekeeping
-	 */
-	if (!housekeeping_cpu(this_cpu, HK_TYPE_SCHED))
-		return;
+	struct cfs_rq *cfs_rq = &rq->cfs;
+	struct sched_entity *se;
+	struct task_struct *p;
+	int new_tasks;
 
-	/* Will wake up very soon. No time for doing anything else*/
-	if (this_rq->avg_idle < sysctl_sched_migration_cost)
-		return;
+again:
+	if (!sched_fair_runnable(rq))
+		goto idle;
 
-	/* Don't need to update blocked load of idle CPUs*/
-	if (!READ_ONCE(nohz.has_blocked) ||
-	    time_before(jiffies, READ_ONCE(nohz.next_blocked)))
-		return;
+#ifdef CONFIG_FAIR_GROUP_SCHED
+	if (!prev || prev->sched_class != &fair_sched_class)
+		goto simple;
 
 	/*
-	 * Set the need to trigger ILB in order to update blocked load
-	 * before entering idle state.
+	 * Because of the set_next_buddy() in dequeue_task_fair() it is rather
+	 * likely that a next task is from the same cgroup as the current.
+	 *
+	 * Therefore attempt to avoid putting and setting the entire cgroup
+	 * hierarchy, only change the part that actually changes.
 	 */
-	atomic_or(NOHZ_NEWILB_KICK, nohz_flags(this_cpu));
-}
 
-#else /* !CONFIG_NO_HZ_COMMON */
-static inline void nohz_balancer_kick(struct rq *rq) { }
-
-static inline bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
-{
-	return false;
-}
+	do {
+		struct sched_entity *curr = cfs_rq->curr;
 
-static inline void nohz_newidle_balance(struct rq *this_rq) { }
-#endif /* CONFIG_NO_HZ_COMMON */
+		/*
+		 * Since we got here without doing put_prev_entity() we also
+		 * have to consider cfs_rq->curr. If it is still a runnable
+		 * entity, update_curr() will update its vruntime, otherwise
+		 * forget we've ever seen it.
+		 */
+		if (curr) {
+			if (curr->on_rq)
+				update_curr(cfs_rq);
+			else
+				curr = NULL;
 
-/*
- * sched_balance_newidle is called by schedule() if this_cpu is about to become
- * idle. Attempts to pull tasks from other CPUs.
- *
- * Returns:
- *   < 0 - we released the lock and there are !fair tasks present
- *     0 - failed, no new tasks
- *   > 0 - success, new (fair) tasks present
- */
-static int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf)
-{
-	unsigned long next_balance = jiffies + HZ;
-	int this_cpu = this_rq->cpu;
-	int continue_balancing = 1;
-	u64 t0, t1, curr_cost = 0;
-	struct sched_domain *sd;
-	int pulled_task = 0;
+			/*
+			 * This call to check_cfs_rq_runtime() will do the
+			 * throttle and dequeue its entity in the parent(s).
+			 * Therefore the nr_running test will indeed
+			 * be correct.
+			 */
+			if (unlikely(check_cfs_rq_runtime(cfs_rq))) {
+				cfs_rq = &rq->cfs;
 
-	update_misfit_status(NULL, this_rq);
+				if (!cfs_rq->nr_running)
+					goto idle;
 
-	/*
-	 * There is a task waiting to run. No need to search for one.
-	 * Return 0; the task will be enqueued when switching to idle.
-	 */
-	if (this_rq->ttwu_pending)
-		return 0;
+				goto simple;
+			}
+		}
 
-	/*
-	 * We must set idle_stamp _before_ calling sched_balance_rq()
-	 * for CPU_NEWLY_IDLE, such that we measure the this duration
-	 * as idle time.
-	 */
-	this_rq->idle_stamp = rq_clock(this_rq);
+		se = pick_next_entity(cfs_rq);
+		cfs_rq = group_cfs_rq(se);
+	} while (cfs_rq);
 
-	/*
-	 * Do not pull tasks towards !active CPUs...
-	 */
-	if (!cpu_active(this_cpu))
-		return 0;
+	p = task_of(se);
 
 	/*
-	 * This is OK, because current is on_cpu, which avoids it being picked
-	 * for load-balance and preemption/IRQs are still disabled avoiding
-	 * further scheduler activity on it and we're being very careful to
-	 * re-start the picking loop.
+	 * Since we haven't yet done put_prev_entity and if the selected task
+	 * is a different task than we started out with, try and touch the
+	 * least amount of cfs_rqs.
 	 */
-	rq_unpin_lock(this_rq, rf);
-
-	rcu_read_lock();
-	sd = rcu_dereference_check_sched_domain(this_rq->sd);
+	if (prev != p) {
+		struct sched_entity *pse = &prev->se;
 
-	if (!get_rd_overloaded(this_rq->rd) ||
-	    (sd && this_rq->avg_idle < sd->max_newidle_lb_cost)) {
+		while (!(cfs_rq = is_same_group(se, pse))) {
+			int se_depth = se->depth;
+			int pse_depth = pse->depth;
 
-		if (sd)
-			update_next_balance(sd, &next_balance);
-		rcu_read_unlock();
+			if (se_depth <= pse_depth) {
+				put_prev_entity(cfs_rq_of(pse), pse);
+				pse = parent_entity(pse);
+			}
+			if (se_depth >= pse_depth) {
+				set_next_entity(cfs_rq_of(se), se);
+				se = parent_entity(se);
+			}
+		}
 
-		goto out;
+		put_prev_entity(cfs_rq, pse);
+		set_next_entity(cfs_rq, se);
 	}
-	rcu_read_unlock();
-
-	raw_spin_rq_unlock(this_rq);
 
-	t0 = sched_clock_cpu(this_cpu);
-	sched_balance_update_blocked_averages(this_cpu);
-
-	rcu_read_lock();
-	for_each_domain(this_cpu, sd) {
-		u64 domain_cost;
-
-		update_next_balance(sd, &next_balance);
+	goto done;
+simple:
+#endif
+	if (prev)
+		put_prev_task(rq, prev);
 
-		if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost)
-			break;
+	do {
+		se = pick_next_entity(cfs_rq);
+		set_next_entity(cfs_rq, se);
+		cfs_rq = group_cfs_rq(se);
+	} while (cfs_rq);
 
-		if (sd->flags & SD_BALANCE_NEWIDLE) {
+	p = task_of(se);
 
-			pulled_task = sched_balance_rq(this_cpu, this_rq,
-						   sd, CPU_NEWLY_IDLE,
-						   &continue_balancing);
+done: __maybe_unused;
+#ifdef CONFIG_SMP
+	/*
+	 * Move the next running task to the front of
+	 * the list, so our cfs_tasks list becomes MRU
+	 * one.
+	 */
+	list_move(&p->se.group_node, &rq->cfs_tasks);
+#endif
 
-			t1 = sched_clock_cpu(this_cpu);
-			domain_cost = t1 - t0;
-			update_newidle_cost(sd, domain_cost);
+	if (hrtick_enabled_fair(rq))
+		hrtick_start_fair(rq, p);
 
-			curr_cost += domain_cost;
-			t0 = t1;
-		}
+	update_misfit_status(p, rq);
+	sched_fair_update_stop_tick(rq, p);
 
-		/*
-		 * Stop searching for tasks to pull if there are
-		 * now runnable tasks on this rq.
-		 */
-		if (pulled_task || !continue_balancing)
-			break;
-	}
-	rcu_read_unlock();
+	return p;
 
-	raw_spin_rq_lock(this_rq);
+idle:
+	if (!rf)
+		return NULL;
 
-	if (curr_cost > this_rq->max_idle_balance_cost)
-		this_rq->max_idle_balance_cost = curr_cost;
+	new_tasks = sched_balance_newidle(rq, rf);
 
 	/*
-	 * While browsing the domains, we released the rq lock, a task could
-	 * have been enqueued in the meantime. Since we're not going idle,
-	 * pretend we pulled a task.
+	 * Because sched_balance_newidle() releases (and re-acquires) rq->lock, it is
+	 * possible for any higher priority task to appear. In that case we
+	 * must re-start the pick_next_entity() loop.
 	 */
-	if (this_rq->cfs.h_nr_running && !pulled_task)
-		pulled_task = 1;
-
-	/* Is there a task of a high priority class? */
-	if (this_rq->nr_running != this_rq->cfs.h_nr_running)
-		pulled_task = -1;
+	if (new_tasks < 0)
+		return RETRY_TASK;
 
-out:
-	/* Move the next balance forward */
-	if (time_after(this_rq->next_balance, next_balance))
-		this_rq->next_balance = next_balance;
+	if (new_tasks > 0)
+		goto again;
 
-	if (pulled_task)
-		this_rq->idle_stamp = 0;
-	else
-		nohz_newidle_balance(this_rq);
+	/*
+	 * rq is about to be idle, check if we need to update the
+	 * lost_idle_time of clock_pelt
+	 */
+	update_idle_rq_clock_pelt(rq);
 
-	rq_repin_lock(this_rq, rf);
+	return NULL;
+}
 
-	return pulled_task;
+static struct task_struct *__pick_next_task_fair(struct rq *rq)
+{
+	return pick_next_task_fair(rq, NULL, NULL);
 }
 
 /*
- * This softirq handler is triggered via SCHED_SOFTIRQ from two places:
- *
- * - directly from the local scheduler_tick() for periodic load balancing
- *
- * - indirectly from a remote scheduler_tick() for NOHZ idle balancing
- *   through the SMP cross-call nohz_csd_func()
+ * Account for a descheduled task:
  */
-static __latent_entropy void sched_balance_softirq(struct softirq_action *h)
+static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
 {
-	struct rq *this_rq = this_rq();
-	enum cpu_idle_type idle = this_rq->idle_balance;
-	/*
-	 * If this CPU has a pending NOHZ_BALANCE_KICK, then do the
-	 * balancing on behalf of the other idle CPUs whose ticks are
-	 * stopped. Do nohz_idle_balance *before* sched_balance_domains to
-	 * give the idle CPUs a chance to load balance. Else we may
-	 * load balance only within the local sched_domain hierarchy
-	 * and abort nohz_idle_balance altogether if we pull some load.
-	 */
-	if (nohz_idle_balance(this_rq, idle))
-		return;
+	struct sched_entity *se = &prev->se;
+	struct cfs_rq *cfs_rq;
 
-	/* normal load balance */
-	sched_balance_update_blocked_averages(this_rq->cpu);
-	sched_balance_domains(this_rq, idle);
+	for_each_sched_entity(se) {
+		cfs_rq = cfs_rq_of(se);
+		put_prev_entity(cfs_rq, se);
+	}
 }
 
 /*
- * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
+ * sched_yield() is very simple
  */
-void sched_balance_trigger(struct rq *rq)
+static void yield_task_fair(struct rq *rq)
 {
+	struct task_struct *curr = rq->curr;
+	struct cfs_rq *cfs_rq = task_cfs_rq(curr);
+	struct sched_entity *se = &curr->se;
+
 	/*
-	 * Don't need to rebalance while attached to NULL domain or
-	 * runqueue CPU is not active
+	 * Are we the only task in the tree?
 	 */
-	if (unlikely(on_null_domain(rq) || !cpu_active(cpu_of(rq))))
+	if (unlikely(rq->nr_running == 1))
 		return;
 
-	if (time_after_eq(jiffies, rq->next_balance))
-		raise_softirq(SCHED_SOFTIRQ);
+	clear_buddies(cfs_rq, se);
+
+	update_rq_clock(rq);
+	/*
+	 * Update run-time statistics of the 'current'.
+	 */
+	update_curr(cfs_rq);
+	/*
+	 * Tell update_rq_clock() that we've just updated,
+	 * so we don't do microscopic update in schedule()
+	 * and double the fastpath cost.
+	 */
+	rq_clock_skip_update(rq);
+
+	se->deadline += calc_delta_fair(se->slice, se);
+}
+
+static bool yield_to_task_fair(struct rq *rq, struct task_struct *p)
+{
+	struct sched_entity *se = &p->se;
+
+	/* throttled hierarchies are not runnable */
+	if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se)))
+		return false;
+
+	/* Tell the scheduler that we'd really like se to run next. */
+	set_next_buddy(se);
+
+	yield_task_fair(rq);
 
-	nohz_balancer_kick(rq);
+	return true;
 }
 
+#ifdef CONFIG_SMP
+
 static void rq_online_fair(struct rq *rq)
 {
 	update_sysctl();
@@ -13272,24 +8014,12 @@ __init void init_sched_fair_class(void)
 	int i;
 
 	for_each_possible_cpu(i) {
-		zalloc_cpumask_var_node(&per_cpu(load_balance_mask, i), GFP_KERNEL, cpu_to_node(i));
 		zalloc_cpumask_var_node(&per_cpu(select_rq_mask,    i), GFP_KERNEL, cpu_to_node(i));
-		zalloc_cpumask_var_node(&per_cpu(should_we_balance_tmpmask, i),
-					GFP_KERNEL, cpu_to_node(i));
 
 #ifdef CONFIG_CFS_BANDWIDTH
 		INIT_CSD(&cpu_rq(i)->cfsb_csd, __cfsb_csd_unthrottle, cpu_rq(i));
 		INIT_LIST_HEAD(&cpu_rq(i)->cfsb_csd_list);
 #endif
 	}
-
-	open_softirq(SCHED_SOFTIRQ, sched_balance_softirq);
-
-#ifdef CONFIG_NO_HZ_COMMON
-	nohz.next_balance = jiffies;
-	nohz.next_blocked = jiffies;
-	zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
-#endif
 #endif /* SMP */
-
 }
diff --git a/kernel/sched/fair_balance.c b/kernel/sched/fair_balance.c
new file mode 100644
index 000000000000..23b81a526160
--- /dev/null
+++ b/kernel/sched/fair_balance.c
@@ -0,0 +1,5103 @@
+#include <linux/sched.h>
+#include <linux/sched/clock.h>
+#include <linux/sched/isolation.h>
+#include <linux/sched/nohz.h>
+
+#include "sched.h"
+#include "pelt.h"
+
+#ifdef CONFIG_SMP
+
+/* Working cpumask for: sched_balance_rq(), sched_balance_newidle(). */
+static DEFINE_PER_CPU(cpumask_var_t, load_balance_mask);
+static DEFINE_PER_CPU(cpumask_var_t, should_we_balance_tmpmask);
+
+#ifdef CONFIG_NO_HZ_COMMON
+
+static struct {
+	cpumask_var_t idle_cpus_mask;
+	atomic_t nr_cpus;
+	int has_blocked;		/* Idle CPUS has blocked load */
+	int needs_update;		/* Newly idle CPUs need their next_balance collated */
+	unsigned long next_balance;     /* in jiffy units */
+	unsigned long next_blocked;	/* Next update of blocked load in jiffies */
+} nohz ____cacheline_aligned;
+
+#endif /* CONFIG_NO_HZ_COMMON */
+
+/*
+ * cpu_load_without - compute CPU load without any contributions from *p
+ * @cpu: the CPU which load is requested
+ * @p: the task which load should be discounted
+ *
+ * The load of a CPU is defined by the load of tasks currently enqueued on that
+ * CPU as well as tasks which are currently sleeping after an execution on that
+ * CPU.
+ *
+ * This method returns the load of the specified CPU by discounting the load of
+ * the specified task, whenever the task is currently contributing to the CPU
+ * load.
+ */
+unsigned long cpu_load_without(struct rq *rq, struct task_struct *p)
+{
+	struct cfs_rq *cfs_rq;
+	unsigned int load;
+
+	/* Task has no contribution or is new */
+	if (cpu_of(rq) != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
+		return cpu_load(rq);
+
+	cfs_rq = &rq->cfs;
+	load = READ_ONCE(cfs_rq->avg.load_avg);
+
+	/* Discount task's util from CPU's util */
+	lsub_positive(&load, task_h_load(p));
+
+	return load;
+}
+
+
+
+void enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	cfs_rq->avg.load_avg += se->avg.load_avg;
+	cfs_rq->avg.load_sum += se_weight(se) * se->avg.load_sum;
+}
+
+void dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg);
+	sub_positive(&cfs_rq->avg.load_sum, se_weight(se) * se->avg.load_sum);
+	/* See update_cfs_rq_load_avg() */
+	cfs_rq->avg.load_sum = max_t(u32, cfs_rq->avg.load_sum,
+					  cfs_rq->avg.load_avg * PELT_MIN_DIVIDER);
+}
+
+#endif /* CONFIG_SMP */
+
+void cfs_rq_util_change(struct cfs_rq *cfs_rq, int flags)
+{
+	struct rq *rq = rq_of(cfs_rq);
+
+	if (&rq->cfs == cfs_rq) {
+		/*
+		 * There are a few boundary cases this might miss but it should
+		 * get called often enough that that should (hopefully) not be
+		 * a real problem.
+		 *
+		 * It will not get called when we go idle, because the idle
+		 * thread is a different class (!fair), nor will the utilization
+		 * number include things like RT tasks.
+		 *
+		 * As is, the util number is not freq-invariant (we'd have to
+		 * implement arch_scale_freq_capacity() for that).
+		 *
+		 * See cpu_util_cfs().
+		 */
+		cpufreq_update_util(rq, flags);
+	}
+}
+
+#ifdef CONFIG_SMP
+static inline bool load_avg_is_decayed(struct sched_avg *sa)
+{
+	if (sa->load_sum)
+		return false;
+
+	if (sa->util_sum)
+		return false;
+
+	if (sa->runnable_sum)
+		return false;
+
+	/*
+	 * _avg must be null when _sum are null because _avg = _sum / divider
+	 * Make sure that rounding and/or propagation of PELT values never
+	 * break this.
+	 */
+	SCHED_WARN_ON(sa->load_avg ||
+		      sa->util_avg ||
+		      sa->runnable_avg);
+
+	return true;
+}
+
+static inline u64 cfs_rq_last_update_time(struct cfs_rq *cfs_rq)
+{
+	return u64_u32_load_copy(cfs_rq->avg.last_update_time,
+				 cfs_rq->last_update_time_copy);
+}
+#ifdef CONFIG_FAIR_GROUP_SCHED
+/*
+ * Because list_add_leaf_cfs_rq always places a child cfs_rq on the list
+ * immediately before a parent cfs_rq, and cfs_rqs are removed from the list
+ * bottom-up, we only have to test whether the cfs_rq before us on the list
+ * is our child.
+ * If cfs_rq is not on the list, test whether a child needs its to be added to
+ * connect a branch to the tree  * (see list_add_leaf_cfs_rq() for details).
+ */
+static inline bool child_cfs_rq_on_list(struct cfs_rq *cfs_rq)
+{
+	struct cfs_rq *prev_cfs_rq;
+	struct list_head *prev;
+
+	if (cfs_rq->on_list) {
+		prev = cfs_rq->leaf_cfs_rq_list.prev;
+	} else {
+		struct rq *rq = rq_of(cfs_rq);
+
+		prev = rq->tmp_alone_branch;
+	}
+
+	prev_cfs_rq = container_of(prev, struct cfs_rq, leaf_cfs_rq_list);
+
+	return (prev_cfs_rq->tg->parent == cfs_rq->tg);
+}
+
+bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
+{
+	if (cfs_rq->load.weight)
+		return false;
+
+	if (!load_avg_is_decayed(&cfs_rq->avg))
+		return false;
+
+	if (child_cfs_rq_on_list(cfs_rq))
+		return false;
+
+	return true;
+}
+
+/**
+ * update_tg_load_avg - update the tg's load avg
+ * @cfs_rq: the cfs_rq whose avg changed
+ *
+ * This function 'ensures': tg->load_avg := \Sum tg->cfs_rq[]->avg.load.
+ * However, because tg->load_avg is a global value there are performance
+ * considerations.
+ *
+ * In order to avoid having to look at the other cfs_rq's, we use a
+ * differential update where we store the last value we propagated. This in
+ * turn allows skipping updates if the differential is 'small'.
+ *
+ * Updating tg's load_avg is necessary before update_cfs_share().
+ */
+void update_tg_load_avg(struct cfs_rq *cfs_rq)
+{
+	long delta;
+	u64 now;
+
+	/*
+	 * No need to update load_avg for root_task_group as it is not used.
+	 */
+	if (cfs_rq->tg == &root_task_group)
+		return;
+
+	/* rq has been offline and doesn't contribute to the share anymore: */
+	if (!cpu_active(cpu_of(rq_of(cfs_rq))))
+		return;
+
+	/*
+	 * For migration heavy workloads, access to tg->load_avg can be
+	 * unbound. Limit the update rate to at most once per ms.
+	 */
+	now = sched_clock_cpu(cpu_of(rq_of(cfs_rq)));
+	if (now - cfs_rq->last_update_tg_load_avg < NSEC_PER_MSEC)
+		return;
+
+	delta = cfs_rq->avg.load_avg - cfs_rq->tg_load_avg_contrib;
+	if (abs(delta) > cfs_rq->tg_load_avg_contrib / 64) {
+		atomic_long_add(delta, &cfs_rq->tg->load_avg);
+		cfs_rq->tg_load_avg_contrib = cfs_rq->avg.load_avg;
+		cfs_rq->last_update_tg_load_avg = now;
+	}
+}
+
+static inline void clear_tg_load_avg(struct cfs_rq *cfs_rq)
+{
+	long delta;
+	u64 now;
+
+	/*
+	 * No need to update load_avg for root_task_group, as it is not used.
+	 */
+	if (cfs_rq->tg == &root_task_group)
+		return;
+
+	now = sched_clock_cpu(cpu_of(rq_of(cfs_rq)));
+	delta = 0 - cfs_rq->tg_load_avg_contrib;
+	atomic_long_add(delta, &cfs_rq->tg->load_avg);
+	cfs_rq->tg_load_avg_contrib = 0;
+	cfs_rq->last_update_tg_load_avg = now;
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+
+/* CPU offline callback: */
+void clear_tg_offline_cfs_rqs(struct rq *rq)
+{
+	struct task_group *tg;
+
+	lockdep_assert_rq_held(rq);
+
+	/*
+	 * The rq clock has already been updated in
+	 * set_rq_offline(), so we should skip updating
+	 * the rq clock again in unthrottle_cfs_rq().
+	 */
+	rq_clock_start_loop_update(rq);
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(tg, &task_groups, list) {
+		struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
+
+		clear_tg_load_avg(cfs_rq);
+	}
+	rcu_read_unlock();
+
+	rq_clock_stop_loop_update(rq);
+}
+
+#else /* !CONFIG_FAIR_GROUP_SCHED: */
+static inline void clear_tg_offline_cfs_rqs(struct rq *rq) {}
+#endif
+
+/*
+ * Called within set_task_rq() right before setting a task's CPU. The
+ * caller only guarantees p->pi_lock is held; no other assumptions,
+ * including the state of rq->lock, should be made.
+ */
+void set_task_rq_fair(struct sched_entity *se,
+		      struct cfs_rq *prev, struct cfs_rq *next)
+{
+	u64 p_last_update_time;
+	u64 n_last_update_time;
+
+	if (!sched_feat(ATTACH_AGE_LOAD))
+		return;
+
+	/*
+	 * We are supposed to update the task to "current" time, then its up to
+	 * date and ready to go to new CPU/cfs_rq. But we have difficulty in
+	 * getting what current time is, so simply throw away the out-of-date
+	 * time. This will result in the wakee task is less decayed, but giving
+	 * the wakee more load sounds not bad.
+	 */
+	if (!(se->avg.last_update_time && prev))
+		return;
+
+	p_last_update_time = cfs_rq_last_update_time(prev);
+	n_last_update_time = cfs_rq_last_update_time(next);
+
+	__update_load_avg_blocked_se(p_last_update_time, se);
+	se->avg.last_update_time = n_last_update_time;
+}
+
+/*
+ * When on migration a sched_entity joins/leaves the PELT hierarchy, we need to
+ * propagate its contribution. The key to this propagation is the invariant
+ * that for each group:
+ *
+ *   ge->avg == grq->avg						(1)
+ *
+ * _IFF_ we look at the pure running and runnable sums. Because they
+ * represent the very same entity, just at different points in the hierarchy.
+ *
+ * Per the above update_tg_cfs_util() and update_tg_cfs_runnable() are trivial
+ * and simply copies the running/runnable sum over (but still wrong, because
+ * the group entity and group rq do not have their PELT windows aligned).
+ *
+ * However, update_tg_cfs_load() is more complex. So we have:
+ *
+ *   ge->avg.load_avg = ge->load.weight * ge->avg.runnable_avg		(2)
+ *
+ * And since, like util, the runnable part should be directly transferable,
+ * the following would _appear_ to be the straight forward approach:
+ *
+ *   grq->avg.load_avg = grq->load.weight * grq->avg.runnable_avg	(3)
+ *
+ * And per (1) we have:
+ *
+ *   ge->avg.runnable_avg == grq->avg.runnable_avg
+ *
+ * Which gives:
+ *
+ *                      ge->load.weight * grq->avg.load_avg
+ *   ge->avg.load_avg = -----------------------------------		(4)
+ *                               grq->load.weight
+ *
+ * Except that is wrong!
+ *
+ * Because while for entities historical weight is not important and we
+ * really only care about our future and therefore can consider a pure
+ * runnable sum, runqueues can NOT do this.
+ *
+ * We specifically want runqueues to have a load_avg that includes
+ * historical weights. Those represent the blocked load, the load we expect
+ * to (shortly) return to us. This only works by keeping the weights as
+ * integral part of the sum. We therefore cannot decompose as per (3).
+ *
+ * Another reason this doesn't work is that runnable isn't a 0-sum entity.
+ * Imagine a rq with 2 tasks that each are runnable 2/3 of the time. Then the
+ * rq itself is runnable anywhere between 2/3 and 1 depending on how the
+ * runnable section of these tasks overlap (or not). If they were to perfectly
+ * align the rq as a whole would be runnable 2/3 of the time. If however we
+ * always have at least 1 runnable task, the rq as a whole is always runnable.
+ *
+ * So we'll have to approximate.. :/
+ *
+ * Given the constraint:
+ *
+ *   ge->avg.running_sum <= ge->avg.runnable_sum <= LOAD_AVG_MAX
+ *
+ * We can construct a rule that adds runnable to a rq by assuming minimal
+ * overlap.
+ *
+ * On removal, we'll assume each task is equally runnable; which yields:
+ *
+ *   grq->avg.runnable_sum = grq->avg.load_sum / grq->load.weight
+ *
+ * XXX: only do this for the part of runnable > running ?
+ *
+ */
+static inline void
+update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
+{
+	long delta_sum, delta_avg = gcfs_rq->avg.util_avg - se->avg.util_avg;
+	u32 new_sum, divider;
+
+	/* Nothing to update */
+	if (!delta_avg)
+		return;
+
+	/*
+	 * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
+	 * See ___update_load_avg() for details.
+	 */
+	divider = get_pelt_divider(&cfs_rq->avg);
+
+
+	/* Set new sched_entity's utilization */
+	se->avg.util_avg = gcfs_rq->avg.util_avg;
+	new_sum = se->avg.util_avg * divider;
+	delta_sum = (long)new_sum - (long)se->avg.util_sum;
+	se->avg.util_sum = new_sum;
+
+	/* Update parent cfs_rq utilization */
+	add_positive(&cfs_rq->avg.util_avg, delta_avg);
+	add_positive(&cfs_rq->avg.util_sum, delta_sum);
+
+	/* See update_cfs_rq_load_avg() */
+	cfs_rq->avg.util_sum = max_t(u32, cfs_rq->avg.util_sum,
+					  cfs_rq->avg.util_avg * PELT_MIN_DIVIDER);
+}
+
+static inline void
+update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
+{
+	long delta_sum, delta_avg = gcfs_rq->avg.runnable_avg - se->avg.runnable_avg;
+	u32 new_sum, divider;
+
+	/* Nothing to update */
+	if (!delta_avg)
+		return;
+
+	/*
+	 * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
+	 * See ___update_load_avg() for details.
+	 */
+	divider = get_pelt_divider(&cfs_rq->avg);
+
+	/* Set new sched_entity's runnable */
+	se->avg.runnable_avg = gcfs_rq->avg.runnable_avg;
+	new_sum = se->avg.runnable_avg * divider;
+	delta_sum = (long)new_sum - (long)se->avg.runnable_sum;
+	se->avg.runnable_sum = new_sum;
+
+	/* Update parent cfs_rq runnable */
+	add_positive(&cfs_rq->avg.runnable_avg, delta_avg);
+	add_positive(&cfs_rq->avg.runnable_sum, delta_sum);
+	/* See update_cfs_rq_load_avg() */
+	cfs_rq->avg.runnable_sum = max_t(u32, cfs_rq->avg.runnable_sum,
+					      cfs_rq->avg.runnable_avg * PELT_MIN_DIVIDER);
+}
+
+static inline void
+update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
+{
+	long delta_avg, running_sum, runnable_sum = gcfs_rq->prop_runnable_sum;
+	unsigned long load_avg;
+	u64 load_sum = 0;
+	s64 delta_sum;
+	u32 divider;
+
+	if (!runnable_sum)
+		return;
+
+	gcfs_rq->prop_runnable_sum = 0;
+
+	/*
+	 * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
+	 * See ___update_load_avg() for details.
+	 */
+	divider = get_pelt_divider(&cfs_rq->avg);
+
+	if (runnable_sum >= 0) {
+		/*
+		 * Add runnable; clip at LOAD_AVG_MAX. Reflects that until
+		 * the CPU is saturated running == runnable.
+		 */
+		runnable_sum += se->avg.load_sum;
+		runnable_sum = min_t(long, runnable_sum, divider);
+	} else {
+		/*
+		 * Estimate the new unweighted runnable_sum of the gcfs_rq by
+		 * assuming all tasks are equally runnable.
+		 */
+		if (scale_load_down(gcfs_rq->load.weight)) {
+			load_sum = div_u64(gcfs_rq->avg.load_sum,
+				scale_load_down(gcfs_rq->load.weight));
+		}
+
+		/* But make sure to not inflate se's runnable */
+		runnable_sum = min(se->avg.load_sum, load_sum);
+	}
+
+	/*
+	 * runnable_sum can't be lower than running_sum
+	 * Rescale running sum to be in the same range as runnable sum
+	 * running_sum is in [0 : LOAD_AVG_MAX <<  SCHED_CAPACITY_SHIFT]
+	 * runnable_sum is in [0 : LOAD_AVG_MAX]
+	 */
+	running_sum = se->avg.util_sum >> SCHED_CAPACITY_SHIFT;
+	runnable_sum = max(runnable_sum, running_sum);
+
+	load_sum = se_weight(se) * runnable_sum;
+	load_avg = div_u64(load_sum, divider);
+
+	delta_avg = load_avg - se->avg.load_avg;
+	if (!delta_avg)
+		return;
+
+	delta_sum = load_sum - (s64)se_weight(se) * se->avg.load_sum;
+
+	se->avg.load_sum = runnable_sum;
+	se->avg.load_avg = load_avg;
+	add_positive(&cfs_rq->avg.load_avg, delta_avg);
+	add_positive(&cfs_rq->avg.load_sum, delta_sum);
+	/* See update_cfs_rq_load_avg() */
+	cfs_rq->avg.load_sum = max_t(u32, cfs_rq->avg.load_sum,
+					  cfs_rq->avg.load_avg * PELT_MIN_DIVIDER);
+}
+
+static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum)
+{
+	cfs_rq->propagate = 1;
+	cfs_rq->prop_runnable_sum += runnable_sum;
+}
+
+/* Update task and its cfs_rq load average */
+static inline int propagate_entity_load_avg(struct sched_entity *se)
+{
+	struct cfs_rq *cfs_rq, *gcfs_rq;
+
+	if (entity_is_task(se))
+		return 0;
+
+	gcfs_rq = group_cfs_rq(se);
+	if (!gcfs_rq->propagate)
+		return 0;
+
+	gcfs_rq->propagate = 0;
+
+	cfs_rq = cfs_rq_of(se);
+
+	add_tg_cfs_propagate(cfs_rq, gcfs_rq->prop_runnable_sum);
+
+	update_tg_cfs_util(cfs_rq, se, gcfs_rq);
+	update_tg_cfs_runnable(cfs_rq, se, gcfs_rq);
+	update_tg_cfs_load(cfs_rq, se, gcfs_rq);
+
+	trace_pelt_cfs_tp(cfs_rq);
+	trace_pelt_se_tp(se);
+
+	return 1;
+}
+
+/*
+ * Check if we need to update the load and the utilization of a blocked
+ * group_entity:
+ */
+static inline bool skip_blocked_update(struct sched_entity *se)
+{
+	struct cfs_rq *gcfs_rq = group_cfs_rq(se);
+
+	/*
+	 * If sched_entity still have not zero load or utilization, we have to
+	 * decay it:
+	 */
+	if (se->avg.load_avg || se->avg.util_avg)
+		return false;
+
+	/*
+	 * If there is a pending propagation, we have to update the load and
+	 * the utilization of the sched_entity:
+	 */
+	if (gcfs_rq->propagate)
+		return false;
+
+	/*
+	 * Otherwise, the load and the utilization of the sched_entity is
+	 * already zero and there is no pending propagation, so it will be a
+	 * waste of time to try to decay it:
+	 */
+	return true;
+}
+
+#else /* CONFIG_FAIR_GROUP_SCHED */
+
+static inline int propagate_entity_load_avg(struct sched_entity *se)
+{
+	return 0;
+}
+
+static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum) {}
+
+#endif /* CONFIG_FAIR_GROUP_SCHED */
+
+#ifdef CONFIG_NO_HZ_COMMON
+void migrate_se_pelt_lag(struct sched_entity *se)
+{
+	u64 throttled = 0, now, lut;
+	struct cfs_rq *cfs_rq;
+	struct rq *rq;
+	bool is_idle;
+
+	if (load_avg_is_decayed(&se->avg))
+		return;
+
+	cfs_rq = cfs_rq_of(se);
+	rq = rq_of(cfs_rq);
+
+	rcu_read_lock();
+	is_idle = is_idle_task(rcu_dereference(rq->curr));
+	rcu_read_unlock();
+
+	/*
+	 * The lag estimation comes with a cost we don't want to pay all the
+	 * time. Hence, limiting to the case where the source CPU is idle and
+	 * we know we are at the greatest risk to have an outdated clock.
+	 */
+	if (!is_idle)
+		return;
+
+	/*
+	 * Estimated "now" is: last_update_time + cfs_idle_lag + rq_idle_lag, where:
+	 *
+	 *   last_update_time (the cfs_rq's last_update_time)
+	 *	= cfs_rq_clock_pelt()@cfs_rq_idle
+	 *      = rq_clock_pelt()@cfs_rq_idle
+	 *        - cfs->throttled_clock_pelt_time@cfs_rq_idle
+	 *
+	 *   cfs_idle_lag (delta between rq's update and cfs_rq's update)
+	 *      = rq_clock_pelt()@rq_idle - rq_clock_pelt()@cfs_rq_idle
+	 *
+	 *   rq_idle_lag (delta between now and rq's update)
+	 *      = sched_clock_cpu() - rq_clock()@rq_idle
+	 *
+	 * We can then write:
+	 *
+	 *    now = rq_clock_pelt()@rq_idle - cfs->throttled_clock_pelt_time +
+	 *          sched_clock_cpu() - rq_clock()@rq_idle
+	 * Where:
+	 *      rq_clock_pelt()@rq_idle is rq->clock_pelt_idle
+	 *      rq_clock()@rq_idle      is rq->clock_idle
+	 *      cfs->throttled_clock_pelt_time@cfs_rq_idle
+	 *                              is cfs_rq->throttled_pelt_idle
+	 */
+
+#ifdef CONFIG_CFS_BANDWIDTH
+	throttled = u64_u32_load(cfs_rq->throttled_pelt_idle);
+	/* The clock has been stopped for throttling */
+	if (throttled == U64_MAX)
+		return;
+#endif
+	now = u64_u32_load(rq->clock_pelt_idle);
+	/*
+	 * Paired with _update_idle_rq_clock_pelt(). It ensures at the worst case
+	 * is observed the old clock_pelt_idle value and the new clock_idle,
+	 * which lead to an underestimation. The opposite would lead to an
+	 * overestimation.
+	 */
+	smp_rmb();
+	lut = cfs_rq_last_update_time(cfs_rq);
+
+	now -= throttled;
+	if (now < lut)
+		/*
+		 * cfs_rq->avg.last_update_time is more recent than our
+		 * estimation, let's use it.
+		 */
+		now = lut;
+	else
+		now += sched_clock_cpu(cpu_of(rq)) - u64_u32_load(rq->clock_idle);
+
+	__update_load_avg_blocked_se(now, se);
+}
+#endif
+
+/**
+ * update_cfs_rq_load_avg - update the cfs_rq's load/util averages
+ * @now: current time, as per cfs_rq_clock_pelt()
+ * @cfs_rq: cfs_rq to update
+ *
+ * The cfs_rq avg is the direct sum of all its entities (blocked and runnable)
+ * avg. The immediate corollary is that all (fair) tasks must be attached.
+ *
+ * cfs_rq->avg is used for task_h_load() and update_cfs_share() for example.
+ *
+ * Return: true if the load decayed or we removed load.
+ *
+ * Since both these conditions indicate a changed cfs_rq->avg.load we should
+ * call update_tg_load_avg() when this function returns true.
+ */
+static inline int
+update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
+{
+	unsigned long removed_load = 0, removed_util = 0, removed_runnable = 0;
+	struct sched_avg *sa = &cfs_rq->avg;
+	int decayed = 0;
+
+	if (cfs_rq->removed.nr) {
+		unsigned long r;
+		u32 divider = get_pelt_divider(&cfs_rq->avg);
+
+		raw_spin_lock(&cfs_rq->removed.lock);
+		swap(cfs_rq->removed.util_avg, removed_util);
+		swap(cfs_rq->removed.load_avg, removed_load);
+		swap(cfs_rq->removed.runnable_avg, removed_runnable);
+		cfs_rq->removed.nr = 0;
+		raw_spin_unlock(&cfs_rq->removed.lock);
+
+		r = removed_load;
+		sub_positive(&sa->load_avg, r);
+		sub_positive(&sa->load_sum, r * divider);
+		/* See sa->util_sum below */
+		sa->load_sum = max_t(u32, sa->load_sum, sa->load_avg * PELT_MIN_DIVIDER);
+
+		r = removed_util;
+		sub_positive(&sa->util_avg, r);
+		sub_positive(&sa->util_sum, r * divider);
+		/*
+		 * Because of rounding, se->util_sum might ends up being +1 more than
+		 * cfs->util_sum. Although this is not a problem by itself, detaching
+		 * a lot of tasks with the rounding problem between 2 updates of
+		 * util_avg (~1ms) can make cfs->util_sum becoming null whereas
+		 * cfs_util_avg is not.
+		 * Check that util_sum is still above its lower bound for the new
+		 * util_avg. Given that period_contrib might have moved since the last
+		 * sync, we are only sure that util_sum must be above or equal to
+		 *    util_avg * minimum possible divider
+		 */
+		sa->util_sum = max_t(u32, sa->util_sum, sa->util_avg * PELT_MIN_DIVIDER);
+
+		r = removed_runnable;
+		sub_positive(&sa->runnable_avg, r);
+		sub_positive(&sa->runnable_sum, r * divider);
+		/* See sa->util_sum above */
+		sa->runnable_sum = max_t(u32, sa->runnable_sum,
+					      sa->runnable_avg * PELT_MIN_DIVIDER);
+
+		/*
+		 * removed_runnable is the unweighted version of removed_load so we
+		 * can use it to estimate removed_load_sum.
+		 */
+		add_tg_cfs_propagate(cfs_rq,
+			-(long)(removed_runnable * divider) >> SCHED_CAPACITY_SHIFT);
+
+		decayed = 1;
+	}
+
+	decayed |= __update_load_avg_cfs_rq(now, cfs_rq);
+	u64_u32_store_copy(sa->last_update_time,
+			   cfs_rq->last_update_time_copy,
+			   sa->last_update_time);
+	return decayed;
+}
+
+/**
+ * attach_entity_load_avg - attach this entity to its cfs_rq load avg
+ * @cfs_rq: cfs_rq to attach to
+ * @se: sched_entity to attach
+ *
+ * Must call update_cfs_rq_load_avg() before this, since we rely on
+ * cfs_rq->avg.last_update_time being current.
+ */
+void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	/*
+	 * cfs_rq->avg.period_contrib can be used for both cfs_rq and se.
+	 * See ___update_load_avg() for details.
+	 */
+	u32 divider = get_pelt_divider(&cfs_rq->avg);
+
+	/*
+	 * When we attach the @se to the @cfs_rq, we must align the decay
+	 * window because without that, really weird and wonderful things can
+	 * happen.
+	 *
+	 * XXX illustrate
+	 */
+	se->avg.last_update_time = cfs_rq->avg.last_update_time;
+	se->avg.period_contrib = cfs_rq->avg.period_contrib;
+
+	/*
+	 * Hell(o) Nasty stuff.. we need to recompute _sum based on the new
+	 * period_contrib. This isn't strictly correct, but since we're
+	 * entirely outside of the PELT hierarchy, nobody cares if we truncate
+	 * _sum a little.
+	 */
+	se->avg.util_sum = se->avg.util_avg * divider;
+
+	se->avg.runnable_sum = se->avg.runnable_avg * divider;
+
+	se->avg.load_sum = se->avg.load_avg * divider;
+	if (se_weight(se) < se->avg.load_sum)
+		se->avg.load_sum = div_u64(se->avg.load_sum, se_weight(se));
+	else
+		se->avg.load_sum = 1;
+
+	enqueue_load_avg(cfs_rq, se);
+	cfs_rq->avg.util_avg += se->avg.util_avg;
+	cfs_rq->avg.util_sum += se->avg.util_sum;
+	cfs_rq->avg.runnable_avg += se->avg.runnable_avg;
+	cfs_rq->avg.runnable_sum += se->avg.runnable_sum;
+
+	add_tg_cfs_propagate(cfs_rq, se->avg.load_sum);
+
+	cfs_rq_util_change(cfs_rq, 0);
+
+	trace_pelt_cfs_tp(cfs_rq);
+}
+
+/**
+ * detach_entity_load_avg - detach this entity from its cfs_rq load avg
+ * @cfs_rq: cfs_rq to detach from
+ * @se: sched_entity to detach
+ *
+ * Must call update_cfs_rq_load_avg() before this, since we rely on
+ * cfs_rq->avg.last_update_time being current.
+ */
+void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	dequeue_load_avg(cfs_rq, se);
+	sub_positive(&cfs_rq->avg.util_avg, se->avg.util_avg);
+	sub_positive(&cfs_rq->avg.util_sum, se->avg.util_sum);
+	/* See update_cfs_rq_load_avg() */
+	cfs_rq->avg.util_sum = max_t(u32, cfs_rq->avg.util_sum,
+					  cfs_rq->avg.util_avg * PELT_MIN_DIVIDER);
+
+	sub_positive(&cfs_rq->avg.runnable_avg, se->avg.runnable_avg);
+	sub_positive(&cfs_rq->avg.runnable_sum, se->avg.runnable_sum);
+	/* See update_cfs_rq_load_avg() */
+	cfs_rq->avg.runnable_sum = max_t(u32, cfs_rq->avg.runnable_sum,
+					      cfs_rq->avg.runnable_avg * PELT_MIN_DIVIDER);
+
+	add_tg_cfs_propagate(cfs_rq, -se->avg.load_sum);
+
+	cfs_rq_util_change(cfs_rq, 0);
+
+	trace_pelt_cfs_tp(cfs_rq);
+}
+
+/* Update task and its cfs_rq load average */
+void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
+{
+	u64 now = cfs_rq_clock_pelt(cfs_rq);
+	int decayed;
+
+	/*
+	 * Track task load average for carrying it to new CPU after migrated, and
+	 * track group sched_entity load average for task_h_load calculation in migration
+	 */
+	if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD))
+		__update_load_avg_se(now, cfs_rq, se);
+
+	decayed  = update_cfs_rq_load_avg(now, cfs_rq);
+	decayed |= propagate_entity_load_avg(se);
+
+	if (!se->avg.last_update_time && (flags & DO_ATTACH)) {
+
+		/*
+		 * DO_ATTACH means we're here from enqueue_entity().
+		 * !last_update_time means we've passed through
+		 * migrate_task_rq_fair() indicating we migrated.
+		 *
+		 * IOW we're enqueueing a task on a new CPU.
+		 */
+		attach_entity_load_avg(cfs_rq, se);
+		update_tg_load_avg(cfs_rq);
+
+	} else if (flags & DO_DETACH) {
+		/*
+		 * DO_DETACH means we're here from dequeue_entity()
+		 * and we are migrating task out of the CPU.
+		 */
+		detach_entity_load_avg(cfs_rq, se);
+		update_tg_load_avg(cfs_rq);
+	} else if (decayed) {
+		cfs_rq_util_change(cfs_rq, 0);
+
+		if (flags & UPDATE_TG)
+			update_tg_load_avg(cfs_rq);
+	}
+}
+
+/*
+ * Synchronize entity load avg of dequeued entity without locking
+ * the previous rq.
+ */
+void sync_entity_load_avg(struct sched_entity *se)
+{
+	struct cfs_rq *cfs_rq = cfs_rq_of(se);
+	u64 last_update_time;
+
+	last_update_time = cfs_rq_last_update_time(cfs_rq);
+	__update_load_avg_blocked_se(last_update_time, se);
+}
+
+/*
+ * Task first catches up with cfs_rq, and then subtract
+ * itself from the cfs_rq (task must be off the queue now).
+ */
+void remove_entity_load_avg(struct sched_entity *se)
+{
+	struct cfs_rq *cfs_rq = cfs_rq_of(se);
+	unsigned long flags;
+
+	/*
+	 * tasks cannot exit without having gone through wake_up_new_task() ->
+	 * enqueue_task_fair() which will have added things to the cfs_rq,
+	 * so we can remove unconditionally.
+	 */
+
+	sync_entity_load_avg(se);
+
+	raw_spin_lock_irqsave(&cfs_rq->removed.lock, flags);
+	++cfs_rq->removed.nr;
+	cfs_rq->removed.util_avg	+= se->avg.util_avg;
+	cfs_rq->removed.load_avg	+= se->avg.load_avg;
+	cfs_rq->removed.runnable_avg	+= se->avg.runnable_avg;
+	raw_spin_unlock_irqrestore(&cfs_rq->removed.lock, flags);
+}
+
+static inline unsigned long task_runnable(struct task_struct *p)
+{
+	return READ_ONCE(p->se.avg.runnable_avg);
+}
+
+/*
+ * For asym packing, by default the lower numbered CPU has higher priority.
+ */
+int __weak arch_asym_cpu_priority(int cpu)
+{
+	return -cpu;
+}
+
+/*
+ * The margin used when comparing utilization with CPU capacity.
+ *
+ * (default: ~20%)
+ */
+#define fits_capacity(cap, max)	((cap) * 1280 < (max) * 1024)
+
+/*
+ * The margin used when comparing CPU capacities.
+ * is 'cap1' noticeably greater than 'cap2'
+ *
+ * (default: ~5%)
+ */
+#define capacity_greater(cap1, cap2) ((cap1) * 1024 > (cap2) * 1078)
+
+void util_est_enqueue(struct cfs_rq *cfs_rq, struct task_struct *p)
+{
+	unsigned int enqueued;
+
+	if (!sched_feat(UTIL_EST))
+		return;
+
+	/* Update root cfs_rq's estimated utilization */
+	enqueued  = cfs_rq->avg.util_est;
+	enqueued += _task_util_est(p);
+	WRITE_ONCE(cfs_rq->avg.util_est, enqueued);
+
+	trace_sched_util_est_cfs_tp(cfs_rq);
+}
+
+void util_est_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p)
+{
+	unsigned int enqueued;
+
+	if (!sched_feat(UTIL_EST))
+		return;
+
+	/* Update root cfs_rq's estimated utilization */
+	enqueued  = cfs_rq->avg.util_est;
+	enqueued -= min_t(unsigned int, enqueued, _task_util_est(p));
+	WRITE_ONCE(cfs_rq->avg.util_est, enqueued);
+
+	trace_sched_util_est_cfs_tp(cfs_rq);
+}
+
+#define UTIL_EST_MARGIN (SCHED_CAPACITY_SCALE / 100)
+
+void util_est_update(struct cfs_rq *cfs_rq, struct task_struct *p, bool task_sleep)
+{
+	unsigned int ewma, dequeued, last_ewma_diff;
+
+	if (!sched_feat(UTIL_EST))
+		return;
+
+	/*
+	 * Skip update of task's estimated utilization when the task has not
+	 * yet completed an activation, e.g. being migrated.
+	 */
+	if (!task_sleep)
+		return;
+
+	/* Get current estimate of utilization */
+	ewma = READ_ONCE(p->se.avg.util_est);
+
+	/*
+	 * If the PELT values haven't changed since enqueue time,
+	 * skip the util_est update.
+	 */
+	if (ewma & UTIL_AVG_UNCHANGED)
+		return;
+
+	/* Get utilization at dequeue */
+	dequeued = task_util(p);
+
+	/*
+	 * Reset EWMA on utilization increases, the moving average is used only
+	 * to smooth utilization decreases.
+	 */
+	if (ewma <= dequeued) {
+		ewma = dequeued;
+		goto done;
+	}
+
+	/*
+	 * Skip update of task's estimated utilization when its members are
+	 * already ~1% close to its last activation value.
+	 */
+	last_ewma_diff = ewma - dequeued;
+	if (last_ewma_diff < UTIL_EST_MARGIN)
+		goto done;
+
+	/*
+	 * To avoid overestimation of actual task utilization, skip updates if
+	 * we cannot grant there is idle time in this CPU.
+	 */
+	if (dequeued > arch_scale_cpu_capacity(cpu_of(rq_of(cfs_rq))))
+		return;
+
+	/*
+	 * To avoid underestimate of task utilization, skip updates of EWMA if
+	 * we cannot grant that thread got all CPU time it wanted.
+	 */
+	if ((dequeued + UTIL_EST_MARGIN) < task_runnable(p))
+		goto done;
+
+
+	/*
+	 * Update Task's estimated utilization
+	 *
+	 * When *p completes an activation we can consolidate another sample
+	 * of the task size. This is done by using this value to update the
+	 * Exponential Weighted Moving Average (EWMA):
+	 *
+	 *  ewma(t) = w *  task_util(p) + (1-w) * ewma(t-1)
+	 *          = w *  task_util(p) +         ewma(t-1)  - w * ewma(t-1)
+	 *          = w * (task_util(p) -         ewma(t-1)) +     ewma(t-1)
+	 *          = w * (      -last_ewma_diff           ) +     ewma(t-1)
+	 *          = w * (-last_ewma_diff +  ewma(t-1) / w)
+	 *
+	 * Where 'w' is the weight of new samples, which is configured to be
+	 * 0.25, thus making w=1/4 ( >>= UTIL_EST_WEIGHT_SHIFT)
+	 */
+	ewma <<= UTIL_EST_WEIGHT_SHIFT;
+	ewma  -= last_ewma_diff;
+	ewma >>= UTIL_EST_WEIGHT_SHIFT;
+done:
+	ewma |= UTIL_AVG_UNCHANGED;
+	WRITE_ONCE(p->se.avg.util_est, ewma);
+
+	trace_sched_util_est_se_tp(&p->se);
+}
+
+int util_fits_cpu(unsigned long util,
+		  unsigned long uclamp_min,
+		  unsigned long uclamp_max,
+		  int cpu)
+{
+	unsigned long capacity_orig, capacity_orig_thermal;
+	unsigned long capacity = capacity_of(cpu);
+	bool fits, uclamp_max_fits;
+
+	/*
+	 * Check if the real util fits without any uclamp boost/cap applied.
+	 */
+	fits = fits_capacity(util, capacity);
+
+	if (!uclamp_is_used())
+		return fits;
+
+	/*
+	 * We must use arch_scale_cpu_capacity() for comparing against uclamp_min and
+	 * uclamp_max. We only care about capacity pressure (by using
+	 * capacity_of()) for comparing against the real util.
+	 *
+	 * If a task is boosted to 1024 for example, we don't want a tiny
+	 * pressure to skew the check whether it fits a CPU or not.
+	 *
+	 * Similarly if a task is capped to arch_scale_cpu_capacity(little_cpu), it
+	 * should fit a little cpu even if there's some pressure.
+	 *
+	 * Only exception is for thermal pressure since it has a direct impact
+	 * on available OPP of the system.
+	 *
+	 * We honour it for uclamp_min only as a drop in performance level
+	 * could result in not getting the requested minimum performance level.
+	 *
+	 * For uclamp_max, we can tolerate a drop in performance level as the
+	 * goal is to cap the task. So it's okay if it's getting less.
+	 */
+	capacity_orig = arch_scale_cpu_capacity(cpu);
+	capacity_orig_thermal = capacity_orig - arch_scale_thermal_pressure(cpu);
+
+	/*
+	 * We want to force a task to fit a cpu as implied by uclamp_max.
+	 * But we do have some corner cases to cater for..
+	 *
+	 *
+	 *                                 C=z
+	 *   |                             ___
+	 *   |                  C=y       |   |
+	 *   |_ _ _ _ _ _ _ _ _ ___ _ _ _ | _ | _ _ _ _ _  uclamp_max
+	 *   |      C=x        |   |      |   |
+	 *   |      ___        |   |      |   |
+	 *   |     |   |       |   |      |   |    (util somewhere in this region)
+	 *   |     |   |       |   |      |   |
+	 *   |     |   |       |   |      |   |
+	 *   +----------------------------------------
+	 *         CPU0        CPU1       CPU2
+	 *
+	 *   In the above example if a task is capped to a specific performance
+	 *   point, y, then when:
+	 *
+	 *   * util = 80% of x then it does not fit on CPU0 and should migrate
+	 *     to CPU1
+	 *   * util = 80% of y then it is forced to fit on CPU1 to honour
+	 *     uclamp_max request.
+	 *
+	 *   which is what we're enforcing here. A task always fits if
+	 *   uclamp_max <= capacity_orig. But when uclamp_max > capacity_orig,
+	 *   the normal upmigration rules should withhold still.
+	 *
+	 *   Only exception is when we are on max capacity, then we need to be
+	 *   careful not to block overutilized state. This is so because:
+	 *
+	 *     1. There's no concept of capping at max_capacity! We can't go
+	 *        beyond this performance level anyway.
+	 *     2. The system is being saturated when we're operating near
+	 *        max capacity, it doesn't make sense to block overutilized.
+	 */
+	uclamp_max_fits = (capacity_orig == SCHED_CAPACITY_SCALE) && (uclamp_max == SCHED_CAPACITY_SCALE);
+	uclamp_max_fits = !uclamp_max_fits && (uclamp_max <= capacity_orig);
+	fits = fits || uclamp_max_fits;
+
+	/*
+	 *
+	 *                                 C=z
+	 *   |                             ___       (region a, capped, util >= uclamp_max)
+	 *   |                  C=y       |   |
+	 *   |_ _ _ _ _ _ _ _ _ ___ _ _ _ | _ | _ _ _ _ _ uclamp_max
+	 *   |      C=x        |   |      |   |
+	 *   |      ___        |   |      |   |      (region b, uclamp_min <= util <= uclamp_max)
+	 *   |_ _ _|_ _|_ _ _ _| _ | _ _ _| _ | _ _ _ _ _ uclamp_min
+	 *   |     |   |       |   |      |   |
+	 *   |     |   |       |   |      |   |      (region c, boosted, util < uclamp_min)
+	 *   +----------------------------------------
+	 *         CPU0        CPU1       CPU2
+	 *
+	 * a) If util > uclamp_max, then we're capped, we don't care about
+	 *    actual fitness value here. We only care if uclamp_max fits
+	 *    capacity without taking margin/pressure into account.
+	 *    See comment above.
+	 *
+	 * b) If uclamp_min <= util <= uclamp_max, then the normal
+	 *    fits_capacity() rules apply. Except we need to ensure that we
+	 *    enforce we remain within uclamp_max, see comment above.
+	 *
+	 * c) If util < uclamp_min, then we are boosted. Same as (b) but we
+	 *    need to take into account the boosted value fits the CPU without
+	 *    taking margin/pressure into account.
+	 *
+	 * Cases (a) and (b) are handled in the 'fits' variable already. We
+	 * just need to consider an extra check for case (c) after ensuring we
+	 * handle the case uclamp_min > uclamp_max.
+	 */
+	uclamp_min = min(uclamp_min, uclamp_max);
+	if (fits && (util < uclamp_min) && (uclamp_min > capacity_orig_thermal))
+		return -1;
+
+	return fits;
+}
+
+static inline int task_fits_cpu(struct task_struct *p, int cpu)
+{
+	unsigned long uclamp_min = uclamp_eff_value(p, UCLAMP_MIN);
+	unsigned long uclamp_max = uclamp_eff_value(p, UCLAMP_MAX);
+	unsigned long util = task_util_est(p);
+	/*
+	 * Return true only if the cpu fully fits the task requirements, which
+	 * include the utilization but also the performance hints.
+	 */
+	return (util_fits_cpu(util, uclamp_min, uclamp_max, cpu) > 0);
+}
+
+void update_misfit_status(struct task_struct *p, struct rq *rq)
+{
+	int cpu = cpu_of(rq);
+
+	if (!sched_asym_cpucap_active())
+		return;
+
+	/*
+	 * Affinity allows us to go somewhere higher?  Or are we on biggest
+	 * available CPU already? Or do we fit into this CPU ?
+	 */
+	if (!p || (p->nr_cpus_allowed == 1) ||
+	    (arch_scale_cpu_capacity(cpu) == p->max_allowed_capacity) ||
+	    task_fits_cpu(p, cpu)) {
+
+		rq->misfit_task_load = 0;
+		return;
+	}
+
+	/*
+	 * Make sure that misfit_task_load will not be null even if
+	 * task_h_load() returns 0.
+	 */
+	rq->misfit_task_load = max_t(unsigned long, task_h_load(p), 1);
+}
+
+static inline bool cpu_overutilized(int cpu)
+{
+	unsigned long  rq_util_min, rq_util_max;
+
+	if (!sched_energy_enabled())
+		return false;
+
+	rq_util_min = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MIN);
+	rq_util_max = uclamp_rq_get(cpu_rq(cpu), UCLAMP_MAX);
+
+	/* Return true only if the utilization doesn't fit CPU's capacity */
+	return !util_fits_cpu(cpu_util_cfs(cpu), rq_util_min, rq_util_max, cpu);
+}
+
+static inline void set_rd_overutilized(struct root_domain *rd, bool flag)
+{
+	if (!sched_energy_enabled())
+		return;
+
+	WRITE_ONCE(rd->overutilized, flag);
+	trace_sched_overutilized_tp(rd, flag);
+}
+
+void check_update_overutilized_status(struct rq *rq)
+{
+	/*
+	 * overutilized field is used for load balancing decisions only
+	 * if energy aware scheduler is being used
+	 */
+
+	if (!is_rd_overutilized(rq->rd) && cpu_overutilized(rq->cpu))
+		set_rd_overutilized(rq->rd, 1);
+}
+
+/**************************************************
+ * Fair scheduling class load-balancing methods.
+ *
+ * BASICS
+ *
+ * The purpose of load-balancing is to achieve the same basic fairness the
+ * per-CPU scheduler provides, namely provide a proportional amount of compute
+ * time to each task. This is expressed in the following equation:
+ *
+ *   W_i,n/P_i == W_j,n/P_j for all i,j                               (1)
+ *
+ * Where W_i,n is the n-th weight average for CPU i. The instantaneous weight
+ * W_i,0 is defined as:
+ *
+ *   W_i,0 = \Sum_j w_i,j                                             (2)
+ *
+ * Where w_i,j is the weight of the j-th runnable task on CPU i. This weight
+ * is derived from the nice value as per sched_prio_to_weight[].
+ *
+ * The weight average is an exponential decay average of the instantaneous
+ * weight:
+ *
+ *   W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0               (3)
+ *
+ * C_i is the compute capacity of CPU i, typically it is the
+ * fraction of 'recent' time available for SCHED_OTHER task execution. But it
+ * can also include other factors [XXX].
+ *
+ * To achieve this balance we define a measure of imbalance which follows
+ * directly from (1):
+ *
+ *   imb_i,j = max{ avg(W/C), W_i/C_i } - min{ avg(W/C), W_j/C_j }    (4)
+ *
+ * We them move tasks around to minimize the imbalance. In the continuous
+ * function space it is obvious this converges, in the discrete case we get
+ * a few fun cases generally called infeasible weight scenarios.
+ *
+ * [XXX expand on:
+ *     - infeasible weights;
+ *     - local vs global optima in the discrete case. ]
+ *
+ *
+ * SCHED DOMAINS
+ *
+ * In order to solve the imbalance equation (4), and avoid the obvious O(n^2)
+ * for all i,j solution, we create a tree of CPUs that follows the hardware
+ * topology where each level pairs two lower groups (or better). This results
+ * in O(log n) layers. Furthermore we reduce the number of CPUs going up the
+ * tree to only the first of the previous level and we decrease the frequency
+ * of load-balance at each level inv. proportional to the number of CPUs in
+ * the groups.
+ *
+ * This yields:
+ *
+ *     log_2 n     1     n
+ *   \Sum       { --- * --- * 2^i } = O(n)                            (5)
+ *     i = 0      2^i   2^i
+ *                               `- size of each group
+ *         |         |     `- number of CPUs doing load-balance
+ *         |         `- freq
+ *         `- sum over all levels
+ *
+ * Coupled with a limit on how many tasks we can migrate every balance pass,
+ * this makes (5) the runtime complexity of the balancer.
+ *
+ * An important property here is that each CPU is still (indirectly) connected
+ * to every other CPU in at most O(log n) steps:
+ *
+ * The adjacency matrix of the resulting graph is given by:
+ *
+ *             log_2 n
+ *   A_i,j = \Union     (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1)  (6)
+ *             k = 0
+ *
+ * And you'll find that:
+ *
+ *   A^(log_2 n)_i,j != 0  for all i,j                                (7)
+ *
+ * Showing there's indeed a path between every CPU in at most O(log n) steps.
+ * The task movement gives a factor of O(m), giving a convergence complexity
+ * of:
+ *
+ *   O(nm log n),  n := nr_cpus, m := nr_tasks                        (8)
+ *
+ *
+ * WORK CONSERVING
+ *
+ * In order to avoid CPUs going idle while there's still work to do, new idle
+ * balancing is more aggressive and has the newly idle CPU iterate up the domain
+ * tree itself instead of relying on other CPUs to bring it work.
+ *
+ * This adds some complexity to both (5) and (8) but it reduces the total idle
+ * time.
+ *
+ * [XXX more?]
+ *
+ *
+ * CGROUPS
+ *
+ * Cgroups make a horror show out of (2), instead of a simple sum we get:
+ *
+ *                                s_k,i
+ *   W_i,0 = \Sum_j \Prod_k w_k * -----                               (9)
+ *                                 S_k
+ *
+ * Where
+ *
+ *   s_k,i = \Sum_j w_i,j,k  and  S_k = \Sum_i s_k,i                 (10)
+ *
+ * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on CPU i.
+ *
+ * The big problem is S_k, its a global sum needed to compute a local (W_i)
+ * property.
+ *
+ * [XXX write more on how we solve this.. _after_ merging pjt's patches that
+ *      rewrite all of this once again.]
+ */
+
+static unsigned long __read_mostly max_load_balance_interval = HZ/10;
+
+enum fbq_type { regular, remote, all };
+
+/*
+ * 'group_type' describes the group of CPUs at the moment of load balancing.
+ *
+ * The enum is ordered by pulling priority, with the group with lowest priority
+ * first so the group_type can simply be compared when selecting the busiest
+ * group. See update_sd_pick_busiest().
+ */
+enum group_type {
+	/* The group has spare capacity that can be used to run more tasks.  */
+	group_has_spare = 0,
+	/*
+	 * The group is fully used and the tasks don't compete for more CPU
+	 * cycles. Nevertheless, some tasks might wait before running.
+	 */
+	group_fully_busy,
+	/*
+	 * One task doesn't fit with CPU's capacity and must be migrated to a
+	 * more powerful CPU.
+	 */
+	group_misfit_task,
+	/*
+	 * Balance SMT group that's fully busy. Can benefit from migration
+	 * a task on SMT with busy sibling to another CPU on idle core.
+	 */
+	group_smt_balance,
+	/*
+	 * SD_ASYM_PACKING only: One local CPU with higher capacity is available,
+	 * and the task should be migrated to it instead of running on the
+	 * current CPU.
+	 */
+	group_asym_packing,
+	/*
+	 * The tasks' affinity constraints previously prevented the scheduler
+	 * from balancing the load across the system.
+	 */
+	group_imbalanced,
+	/*
+	 * The CPU is overloaded and can't provide expected CPU cycles to all
+	 * tasks.
+	 */
+	group_overloaded
+};
+
+enum migration_type {
+	migrate_load = 0,
+	migrate_util,
+	migrate_task,
+	migrate_misfit
+};
+
+#define LBF_ALL_PINNED	0x01
+#define LBF_NEED_BREAK	0x02
+#define LBF_DST_PINNED  0x04
+#define LBF_SOME_PINNED	0x08
+#define LBF_ACTIVE_LB	0x10
+
+struct lb_env {
+	struct sched_domain	*sd;
+
+	struct rq		*src_rq;
+	int			src_cpu;
+
+	int			dst_cpu;
+	struct rq		*dst_rq;
+
+	struct cpumask		*dst_grpmask;
+	int			new_dst_cpu;
+	enum cpu_idle_type	idle;
+	long			imbalance;
+	/* The set of CPUs under consideration for load-balancing */
+	struct cpumask		*cpus;
+
+	unsigned int		flags;
+
+	unsigned int		loop;
+	unsigned int		loop_break;
+	unsigned int		loop_max;
+
+	enum fbq_type		fbq_type;
+	enum migration_type	migration_type;
+	struct list_head	tasks;
+};
+
+/*
+ * Is this task likely cache-hot:
+ */
+static int task_hot(struct task_struct *p, struct lb_env *env)
+{
+	s64 delta;
+
+	lockdep_assert_rq_held(env->src_rq);
+
+	if (p->sched_class != &fair_sched_class)
+		return 0;
+
+	if (unlikely(task_has_idle_policy(p)))
+		return 0;
+
+	/* SMT siblings share cache */
+	if (env->sd->flags & SD_SHARE_CPUCAPACITY)
+		return 0;
+
+	/*
+	 * Buddy candidates are cache hot:
+	 */
+	if (sched_feat(CACHE_HOT_BUDDY) && env->dst_rq->nr_running &&
+	    (&p->se == cfs_rq_of(&p->se)->next))
+		return 1;
+
+	if (sysctl_sched_migration_cost == -1)
+		return 1;
+
+	/*
+	 * Don't migrate task if the task's cookie does not match
+	 * with the destination CPU's core cookie.
+	 */
+	if (!sched_core_cookie_match(cpu_rq(env->dst_cpu), p))
+		return 1;
+
+	if (sysctl_sched_migration_cost == 0)
+		return 0;
+
+	delta = rq_clock_task(env->src_rq) - p->se.exec_start;
+
+	return delta < (s64)sysctl_sched_migration_cost;
+}
+
+#ifdef CONFIG_NUMA_BALANCING
+/*
+ * Returns 1, if task migration degrades locality
+ * Returns 0, if task migration improves locality i.e migration preferred.
+ * Returns -1, if task migration is not affected by locality.
+ */
+static int migrate_degrades_locality(struct task_struct *p, struct lb_env *env)
+{
+	struct numa_group *numa_group = rcu_dereference(p->numa_group);
+	unsigned long src_weight, dst_weight;
+	int src_nid, dst_nid, dist;
+
+	if (!static_branch_likely(&sched_numa_balancing))
+		return -1;
+
+	if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
+		return -1;
+
+	src_nid = cpu_to_node(env->src_cpu);
+	dst_nid = cpu_to_node(env->dst_cpu);
+
+	if (src_nid == dst_nid)
+		return -1;
+
+	/* Migrating away from the preferred node is always bad. */
+	if (src_nid == p->numa_preferred_nid) {
+		if (env->src_rq->nr_running > env->src_rq->nr_preferred_running)
+			return 1;
+		else
+			return -1;
+	}
+
+	/* Encourage migration to the preferred node. */
+	if (dst_nid == p->numa_preferred_nid)
+		return 0;
+
+	/* Leaving a core idle is often worse than degrading locality. */
+	if (env->idle == CPU_IDLE)
+		return -1;
+
+	dist = node_distance(src_nid, dst_nid);
+	if (numa_group) {
+		src_weight = group_weight(p, src_nid, dist);
+		dst_weight = group_weight(p, dst_nid, dist);
+	} else {
+		src_weight = task_weight(p, src_nid, dist);
+		dst_weight = task_weight(p, dst_nid, dist);
+	}
+
+	return dst_weight < src_weight;
+}
+
+#else
+static inline int migrate_degrades_locality(struct task_struct *p,
+					     struct lb_env *env)
+{
+	return -1;
+}
+#endif
+
+/*
+ * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
+ */
+static
+int can_migrate_task(struct task_struct *p, struct lb_env *env)
+{
+	int tsk_cache_hot;
+
+	lockdep_assert_rq_held(env->src_rq);
+
+	/*
+	 * We do not migrate tasks that are:
+	 * 1) throttled_lb_pair, or
+	 * 2) cannot be migrated to this CPU due to cpus_ptr, or
+	 * 3) running (obviously), or
+	 * 4) are cache-hot on their current CPU.
+	 */
+	if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))
+		return 0;
+
+	/* Disregard percpu kthreads; they are where they need to be. */
+	if (kthread_is_per_cpu(p))
+		return 0;
+
+	if (!cpumask_test_cpu(env->dst_cpu, p->cpus_ptr)) {
+		int cpu;
+
+		schedstat_inc(p->stats.nr_failed_migrations_affine);
+
+		env->flags |= LBF_SOME_PINNED;
+
+		/*
+		 * Remember if this task can be migrated to any other CPU in
+		 * our sched_group. We may want to revisit it if we couldn't
+		 * meet load balance goals by pulling other tasks on src_cpu.
+		 *
+		 * Avoid computing new_dst_cpu
+		 * - for NEWLY_IDLE
+		 * - if we have already computed one in current iteration
+		 * - if it's an active balance
+		 */
+		if (env->idle == CPU_NEWLY_IDLE ||
+		    env->flags & (LBF_DST_PINNED | LBF_ACTIVE_LB))
+			return 0;
+
+		/* Prevent to re-select dst_cpu via env's CPUs: */
+		for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) {
+			if (cpumask_test_cpu(cpu, p->cpus_ptr)) {
+				env->flags |= LBF_DST_PINNED;
+				env->new_dst_cpu = cpu;
+				break;
+			}
+		}
+
+		return 0;
+	}
+
+	/* Record that we found at least one task that could run on dst_cpu */
+	env->flags &= ~LBF_ALL_PINNED;
+
+	if (task_on_cpu(env->src_rq, p)) {
+		schedstat_inc(p->stats.nr_failed_migrations_running);
+		return 0;
+	}
+
+	/*
+	 * Aggressive migration if:
+	 * 1) active balance
+	 * 2) destination numa is preferred
+	 * 3) task is cache cold, or
+	 * 4) too many balance attempts have failed.
+	 */
+	if (env->flags & LBF_ACTIVE_LB)
+		return 1;
+
+	tsk_cache_hot = migrate_degrades_locality(p, env);
+	if (tsk_cache_hot == -1)
+		tsk_cache_hot = task_hot(p, env);
+
+	if (tsk_cache_hot <= 0 ||
+	    env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
+		if (tsk_cache_hot == 1) {
+			schedstat_inc(env->sd->lb_hot_gained[env->idle]);
+			schedstat_inc(p->stats.nr_forced_migrations);
+		}
+		return 1;
+	}
+
+	schedstat_inc(p->stats.nr_failed_migrations_hot);
+	return 0;
+}
+
+/*
+ * detach_task() -- detach the task for the migration specified in env
+ */
+static void detach_task(struct task_struct *p, struct lb_env *env)
+{
+	lockdep_assert_rq_held(env->src_rq);
+
+	deactivate_task(env->src_rq, p, DEQUEUE_NOCLOCK);
+	set_task_cpu(p, env->dst_cpu);
+}
+
+/*
+ * detach_one_task() -- tries to dequeue exactly one task from env->src_rq, as
+ * part of active balancing operations within "domain".
+ *
+ * Returns a task if successful and NULL otherwise.
+ */
+static struct task_struct *detach_one_task(struct lb_env *env)
+{
+	struct task_struct *p;
+
+	lockdep_assert_rq_held(env->src_rq);
+
+	list_for_each_entry_reverse(p,
+			&env->src_rq->cfs_tasks, se.group_node) {
+		if (!can_migrate_task(p, env))
+			continue;
+
+		detach_task(p, env);
+
+		/*
+		 * Right now, this is only the second place where
+		 * lb_gained[env->idle] is updated (other is detach_tasks)
+		 * so we can safely collect stats here rather than
+		 * inside detach_tasks().
+		 */
+		schedstat_inc(env->sd->lb_gained[env->idle]);
+		return p;
+	}
+	return NULL;
+}
+
+/*
+ * detach_tasks() -- tries to detach up to imbalance load/util/tasks from
+ * busiest_rq, as part of a balancing operation within domain "sd".
+ *
+ * Returns number of detached tasks if successful and 0 otherwise.
+ */
+static int detach_tasks(struct lb_env *env)
+{
+	struct list_head *tasks = &env->src_rq->cfs_tasks;
+	unsigned long util, load;
+	struct task_struct *p;
+	int detached = 0;
+
+	lockdep_assert_rq_held(env->src_rq);
+
+	/*
+	 * Source run queue has been emptied by another CPU, clear
+	 * LBF_ALL_PINNED flag as we will not test any task.
+	 */
+	if (env->src_rq->nr_running <= 1) {
+		env->flags &= ~LBF_ALL_PINNED;
+		return 0;
+	}
+
+	if (env->imbalance <= 0)
+		return 0;
+
+	while (!list_empty(tasks)) {
+		/*
+		 * We don't want to steal all, otherwise we may be treated likewise,
+		 * which could at worst lead to a livelock crash.
+		 */
+		if (env->idle && env->src_rq->nr_running <= 1)
+			break;
+
+		env->loop++;
+		/*
+		 * We've more or less seen every task there is, call it quits
+		 * unless we haven't found any movable task yet.
+		 */
+		if (env->loop > env->loop_max &&
+		    !(env->flags & LBF_ALL_PINNED))
+			break;
+
+		/* take a breather every nr_migrate tasks */
+		if (env->loop > env->loop_break) {
+			env->loop_break += SCHED_NR_MIGRATE_BREAK;
+			env->flags |= LBF_NEED_BREAK;
+			break;
+		}
+
+		p = list_last_entry(tasks, struct task_struct, se.group_node);
+
+		if (!can_migrate_task(p, env))
+			goto next;
+
+		switch (env->migration_type) {
+		case migrate_load:
+			/*
+			 * Depending of the number of CPUs and tasks and the
+			 * cgroup hierarchy, task_h_load() can return a null
+			 * value. Make sure that env->imbalance decreases
+			 * otherwise detach_tasks() will stop only after
+			 * detaching up to loop_max tasks.
+			 */
+			load = max_t(unsigned long, task_h_load(p), 1);
+
+			if (sched_feat(LB_MIN) &&
+			    load < 16 && !env->sd->nr_balance_failed)
+				goto next;
+
+			/*
+			 * Make sure that we don't migrate too much load.
+			 * Nevertheless, let relax the constraint if
+			 * scheduler fails to find a good waiting task to
+			 * migrate.
+			 */
+			if (shr_bound(load, env->sd->nr_balance_failed) > env->imbalance)
+				goto next;
+
+			env->imbalance -= load;
+			break;
+
+		case migrate_util:
+			util = task_util_est(p);
+
+			if (shr_bound(util, env->sd->nr_balance_failed) > env->imbalance)
+				goto next;
+
+			env->imbalance -= util;
+			break;
+
+		case migrate_task:
+			env->imbalance--;
+			break;
+
+		case migrate_misfit:
+			/* This is not a misfit task */
+			if (task_fits_cpu(p, env->src_cpu))
+				goto next;
+
+			env->imbalance = 0;
+			break;
+		}
+
+		detach_task(p, env);
+		list_add(&p->se.group_node, &env->tasks);
+
+		detached++;
+
+#ifdef CONFIG_PREEMPTION
+		/*
+		 * NEWIDLE balancing is a source of latency, so preemptible
+		 * kernels will stop after the first task is detached to minimize
+		 * the critical section.
+		 */
+		if (env->idle == CPU_NEWLY_IDLE)
+			break;
+#endif
+
+		/*
+		 * We only want to steal up to the prescribed amount of
+		 * load/util/tasks.
+		 */
+		if (env->imbalance <= 0)
+			break;
+
+		continue;
+next:
+		list_move(&p->se.group_node, tasks);
+	}
+
+	/*
+	 * Right now, this is one of only two places we collect this stat
+	 * so we can safely collect detach_one_task() stats here rather
+	 * than inside detach_one_task().
+	 */
+	schedstat_add(env->sd->lb_gained[env->idle], detached);
+
+	return detached;
+}
+
+/*
+ * attach_task() -- attach the task detached by detach_task() to its new rq.
+ */
+static void attach_task(struct rq *rq, struct task_struct *p)
+{
+	lockdep_assert_rq_held(rq);
+
+	WARN_ON_ONCE(task_rq(p) != rq);
+	activate_task(rq, p, ENQUEUE_NOCLOCK);
+	wakeup_preempt(rq, p, 0);
+}
+
+/*
+ * attach_one_task() -- attaches the task returned from detach_one_task() to
+ * its new rq.
+ */
+static void attach_one_task(struct rq *rq, struct task_struct *p)
+{
+	struct rq_flags rf;
+
+	rq_lock(rq, &rf);
+	update_rq_clock(rq);
+	attach_task(rq, p);
+	rq_unlock(rq, &rf);
+}
+
+/*
+ * attach_tasks() -- attaches all tasks detached by detach_tasks() to their
+ * new rq.
+ */
+static void attach_tasks(struct lb_env *env)
+{
+	struct list_head *tasks = &env->tasks;
+	struct task_struct *p;
+	struct rq_flags rf;
+
+	rq_lock(env->dst_rq, &rf);
+	update_rq_clock(env->dst_rq);
+
+	while (!list_empty(tasks)) {
+		p = list_first_entry(tasks, struct task_struct, se.group_node);
+		list_del_init(&p->se.group_node);
+
+		attach_task(env->dst_rq, p);
+	}
+
+	rq_unlock(env->dst_rq, &rf);
+}
+
+#ifdef CONFIG_NO_HZ_COMMON
+static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq)
+{
+	if (cfs_rq->avg.load_avg)
+		return true;
+
+	if (cfs_rq->avg.util_avg)
+		return true;
+
+	return false;
+}
+
+static inline bool others_have_blocked(struct rq *rq)
+{
+	if (cpu_util_rt(rq))
+		return true;
+
+	if (cpu_util_dl(rq))
+		return true;
+
+	if (thermal_load_avg(rq))
+		return true;
+
+	if (cpu_util_irq(rq))
+		return true;
+
+	return false;
+}
+
+static inline void update_blocked_load_tick(struct rq *rq)
+{
+	WRITE_ONCE(rq->last_blocked_load_update_tick, jiffies);
+}
+
+static inline void update_blocked_load_status(struct rq *rq, bool has_blocked)
+{
+	if (!has_blocked)
+		rq->has_blocked_load = 0;
+}
+#else
+static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq) { return false; }
+static inline bool others_have_blocked(struct rq *rq) { return false; }
+static inline void update_blocked_load_tick(struct rq *rq) {}
+static inline void update_blocked_load_status(struct rq *rq, bool has_blocked) {}
+#endif
+
+static bool __update_blocked_others(struct rq *rq, bool *done)
+{
+	const struct sched_class *curr_class;
+	u64 now = rq_clock_pelt(rq);
+	unsigned long thermal_pressure;
+	bool decayed;
+
+	/*
+	 * update_load_avg() can call cpufreq_update_util(). Make sure that RT,
+	 * DL and IRQ signals have been updated before updating CFS.
+	 */
+	curr_class = rq->curr->sched_class;
+
+	thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
+
+	decayed = update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) |
+		  update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) |
+		  update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure) |
+		  update_irq_load_avg(rq, 0);
+
+	if (others_have_blocked(rq))
+		*done = false;
+
+	return decayed;
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+
+static bool __update_blocked_fair(struct rq *rq, bool *done)
+{
+	struct cfs_rq *cfs_rq, *pos;
+	bool decayed = false;
+	int cpu = cpu_of(rq);
+
+	/*
+	 * Iterates the task_group tree in a bottom up fashion, see
+	 * list_add_leaf_cfs_rq() for details.
+	 */
+	for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos) {
+		struct sched_entity *se;
+
+		if (update_cfs_rq_load_avg(cfs_rq_clock_pelt(cfs_rq), cfs_rq)) {
+			update_tg_load_avg(cfs_rq);
+
+			if (cfs_rq->nr_running == 0)
+				update_idle_cfs_rq_clock_pelt(cfs_rq);
+
+			if (cfs_rq == &rq->cfs)
+				decayed = true;
+		}
+
+		/* Propagate pending load changes to the parent, if any: */
+		se = cfs_rq->tg->se[cpu];
+		if (se && !skip_blocked_update(se))
+			update_load_avg(cfs_rq_of(se), se, UPDATE_TG);
+
+		/*
+		 * There can be a lot of idle CPU cgroups.  Don't let fully
+		 * decayed cfs_rqs linger on the list.
+		 */
+		if (cfs_rq_is_decayed(cfs_rq))
+			list_del_leaf_cfs_rq(cfs_rq);
+
+		/* Don't need periodic decay once load/util_avg are null */
+		if (cfs_rq_has_blocked(cfs_rq))
+			*done = false;
+	}
+
+	return decayed;
+}
+
+/*
+ * Compute the hierarchical load factor for cfs_rq and all its ascendants.
+ * This needs to be done in a top-down fashion because the load of a child
+ * group is a fraction of its parents load.
+ */
+static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq)
+{
+	struct rq *rq = rq_of(cfs_rq);
+	struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)];
+	unsigned long now = jiffies;
+	unsigned long load;
+
+	if (cfs_rq->last_h_load_update == now)
+		return;
+
+	WRITE_ONCE(cfs_rq->h_load_next, NULL);
+	for_each_sched_entity(se) {
+		cfs_rq = cfs_rq_of(se);
+		WRITE_ONCE(cfs_rq->h_load_next, se);
+		if (cfs_rq->last_h_load_update == now)
+			break;
+	}
+
+	if (!se) {
+		cfs_rq->h_load = cfs_rq_load_avg(cfs_rq);
+		cfs_rq->last_h_load_update = now;
+	}
+
+	while ((se = READ_ONCE(cfs_rq->h_load_next)) != NULL) {
+		load = cfs_rq->h_load;
+		load = div64_ul(load * se->avg.load_avg,
+			cfs_rq_load_avg(cfs_rq) + 1);
+		cfs_rq = group_cfs_rq(se);
+		cfs_rq->h_load = load;
+		cfs_rq->last_h_load_update = now;
+	}
+}
+
+unsigned long task_h_load(struct task_struct *p)
+{
+	struct cfs_rq *cfs_rq = task_cfs_rq(p);
+
+	update_cfs_rq_h_load(cfs_rq);
+	return div64_ul(p->se.avg.load_avg * cfs_rq->h_load,
+			cfs_rq_load_avg(cfs_rq) + 1);
+}
+#else
+static bool __update_blocked_fair(struct rq *rq, bool *done)
+{
+	struct cfs_rq *cfs_rq = &rq->cfs;
+	bool decayed;
+
+	decayed = update_cfs_rq_load_avg(cfs_rq_clock_pelt(cfs_rq), cfs_rq);
+	if (cfs_rq_has_blocked(cfs_rq))
+		*done = false;
+
+	return decayed;
+}
+
+#endif
+
+
+static void sched_balance_update_blocked_averages(int cpu)
+{
+	bool decayed = false, done = true;
+	struct rq *rq = cpu_rq(cpu);
+	struct rq_flags rf;
+
+	rq_lock_irqsave(rq, &rf);
+	update_blocked_load_tick(rq);
+	update_rq_clock(rq);
+
+	decayed |= __update_blocked_others(rq, &done);
+	decayed |= __update_blocked_fair(rq, &done);
+
+	update_blocked_load_status(rq, !done);
+	if (decayed)
+		cpufreq_update_util(rq, 0);
+	rq_unlock_irqrestore(rq, &rf);
+}
+
+/********** Helpers for sched_balance_find_src_group ************************/
+
+/*
+ * sg_lb_stats - stats of a sched_group required for load-balancing:
+ */
+struct sg_lb_stats {
+	unsigned long avg_load;			/* Avg load            over the CPUs of the group */
+	unsigned long group_load;		/* Total load          over the CPUs of the group */
+	unsigned long group_capacity;		/* Capacity            over the CPUs of the group */
+	unsigned long group_util;		/* Total utilization   over the CPUs of the group */
+	unsigned long group_runnable;		/* Total runnable time over the CPUs of the group */
+	unsigned int sum_nr_running;		/* Nr of all tasks running in the group */
+	unsigned int sum_h_nr_running;		/* Nr of CFS tasks running in the group */
+	unsigned int idle_cpus;                 /* Nr of idle CPUs         in the group */
+	unsigned int group_weight;
+	enum group_type group_type;
+	unsigned int group_asym_packing;	/* Tasks should be moved to preferred CPU */
+	unsigned int group_smt_balance;		/* Task on busy SMT be moved */
+	unsigned long group_misfit_task_load;	/* A CPU has a task too big for its capacity */
+#ifdef CONFIG_NUMA_BALANCING
+	unsigned int nr_numa_running;
+	unsigned int nr_preferred_running;
+#endif
+};
+
+/*
+ * sd_lb_stats - stats of a sched_domain required for load-balancing:
+ */
+struct sd_lb_stats {
+	struct sched_group *busiest;		/* Busiest group in this sd */
+	struct sched_group *local;		/* Local group in this sd */
+	unsigned long total_load;		/* Total load of all groups in sd */
+	unsigned long total_capacity;		/* Total capacity of all groups in sd */
+	unsigned long avg_load;			/* Average load across all groups in sd */
+	unsigned int prefer_sibling;		/* Tasks should go to sibling first */
+
+	struct sg_lb_stats busiest_stat;	/* Statistics of the busiest group */
+	struct sg_lb_stats local_stat;		/* Statistics of the local group */
+};
+
+static inline void init_sd_lb_stats(struct sd_lb_stats *sds)
+{
+	/*
+	 * Skimp on the clearing to avoid duplicate work. We can avoid clearing
+	 * local_stat because update_sg_lb_stats() does a full clear/assignment.
+	 * We must however set busiest_stat::group_type and
+	 * busiest_stat::idle_cpus to the worst busiest group because
+	 * update_sd_pick_busiest() reads these before assignment.
+	 */
+	*sds = (struct sd_lb_stats){
+		.busiest = NULL,
+		.local = NULL,
+		.total_load = 0UL,
+		.total_capacity = 0UL,
+		.busiest_stat = {
+			.idle_cpus = UINT_MAX,
+			.group_type = group_has_spare,
+		},
+	};
+}
+
+static unsigned long scale_rt_capacity(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+	unsigned long max = arch_scale_cpu_capacity(cpu);
+	unsigned long used, free;
+	unsigned long irq;
+
+	irq = cpu_util_irq(rq);
+
+	if (unlikely(irq >= max))
+		return 1;
+
+	/*
+	 * avg_rt.util_avg and avg_dl.util_avg track binary signals
+	 * (running and not running) with weights 0 and 1024 respectively.
+	 * avg_thermal.load_avg tracks thermal pressure and the weighted
+	 * average uses the actual delta max capacity(load).
+	 */
+	used = cpu_util_rt(rq);
+	used += cpu_util_dl(rq);
+	used += thermal_load_avg(rq);
+
+	if (unlikely(used >= max))
+		return 1;
+
+	free = max - used;
+
+	return scale_irq_capacity(free, irq, max);
+}
+
+static void update_cpu_capacity(struct sched_domain *sd, int cpu)
+{
+	unsigned long capacity = scale_rt_capacity(cpu);
+	struct sched_group *sdg = sd->groups;
+
+	if (!capacity)
+		capacity = 1;
+
+	cpu_rq(cpu)->cpu_capacity = capacity;
+	trace_sched_cpu_capacity_tp(cpu_rq(cpu));
+
+	sdg->sgc->capacity = capacity;
+	sdg->sgc->min_capacity = capacity;
+	sdg->sgc->max_capacity = capacity;
+}
+
+void update_group_capacity(struct sched_domain *sd, int cpu)
+{
+	struct sched_domain *child = sd->child;
+	struct sched_group *group, *sdg = sd->groups;
+	unsigned long capacity, min_capacity, max_capacity;
+	unsigned long interval;
+
+	interval = msecs_to_jiffies(sd->balance_interval);
+	interval = clamp(interval, 1UL, max_load_balance_interval);
+	sdg->sgc->next_update = jiffies + interval;
+
+	if (!child) {
+		update_cpu_capacity(sd, cpu);
+		return;
+	}
+
+	capacity = 0;
+	min_capacity = ULONG_MAX;
+	max_capacity = 0;
+
+	if (child->flags & SD_OVERLAP) {
+		/*
+		 * SD_OVERLAP domains cannot assume that child groups
+		 * span the current group.
+		 */
+
+		for_each_cpu(cpu, sched_group_span(sdg)) {
+			unsigned long cpu_cap = capacity_of(cpu);
+
+			capacity += cpu_cap;
+			min_capacity = min(cpu_cap, min_capacity);
+			max_capacity = max(cpu_cap, max_capacity);
+		}
+	} else  {
+		/*
+		 * !SD_OVERLAP domains can assume that child groups
+		 * span the current group.
+		 */
+
+		group = child->groups;
+		do {
+			struct sched_group_capacity *sgc = group->sgc;
+
+			capacity += sgc->capacity;
+			min_capacity = min(sgc->min_capacity, min_capacity);
+			max_capacity = max(sgc->max_capacity, max_capacity);
+			group = group->next;
+		} while (group != child->groups);
+	}
+
+	sdg->sgc->capacity = capacity;
+	sdg->sgc->min_capacity = min_capacity;
+	sdg->sgc->max_capacity = max_capacity;
+}
+
+/*
+ * Check whether the capacity of the rq has been noticeably reduced by side
+ * activity. The imbalance_pct is used for the threshold.
+ * Return true is the capacity is reduced
+ */
+static inline int
+check_cpu_capacity(struct rq *rq, struct sched_domain *sd)
+{
+	return ((rq->cpu_capacity * sd->imbalance_pct) <
+				(arch_scale_cpu_capacity(cpu_of(rq)) * 100));
+}
+
+/* Check if the rq has a misfit task */
+static inline bool check_misfit_status(struct rq *rq)
+{
+	return rq->misfit_task_load;
+}
+
+/*
+ * Group imbalance indicates (and tries to solve) the problem where balancing
+ * groups is inadequate due to ->cpus_ptr constraints.
+ *
+ * Imagine a situation of two groups of 4 CPUs each and 4 tasks each with a
+ * cpumask covering 1 CPU of the first group and 3 CPUs of the second group.
+ * Something like:
+ *
+ *	{ 0 1 2 3 } { 4 5 6 7 }
+ *	        *     * * *
+ *
+ * If we were to balance group-wise we'd place two tasks in the first group and
+ * two tasks in the second group. Clearly this is undesired as it will overload
+ * cpu 3 and leave one of the CPUs in the second group unused.
+ *
+ * The current solution to this issue is detecting the skew in the first group
+ * by noticing the lower domain failed to reach balance and had difficulty
+ * moving tasks due to affinity constraints.
+ *
+ * When this is so detected; this group becomes a candidate for busiest; see
+ * update_sd_pick_busiest(). And calculate_imbalance() and
+ * sched_balance_find_src_group() avoid some of the usual balance conditions to allow it
+ * to create an effective group imbalance.
+ *
+ * This is a somewhat tricky proposition since the next run might not find the
+ * group imbalance and decide the groups need to be balanced again. A most
+ * subtle and fragile situation.
+ */
+
+static inline int sg_imbalanced(struct sched_group *group)
+{
+	return group->sgc->imbalance;
+}
+
+/*
+ * group_has_capacity returns true if the group has spare capacity that could
+ * be used by some tasks.
+ * We consider that a group has spare capacity if the number of task is
+ * smaller than the number of CPUs or if the utilization is lower than the
+ * available capacity for CFS tasks.
+ * For the latter, we use a threshold to stabilize the state, to take into
+ * account the variance of the tasks' load and to return true if the available
+ * capacity in meaningful for the load balancer.
+ * As an example, an available capacity of 1% can appear but it doesn't make
+ * any benefit for the load balance.
+ */
+static inline bool
+group_has_capacity(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
+{
+	if (sgs->sum_nr_running < sgs->group_weight)
+		return true;
+
+	if ((sgs->group_capacity * imbalance_pct) <
+			(sgs->group_runnable * 100))
+		return false;
+
+	if ((sgs->group_capacity * 100) >
+			(sgs->group_util * imbalance_pct))
+		return true;
+
+	return false;
+}
+
+/*
+ *  group_is_overloaded returns true if the group has more tasks than it can
+ *  handle.
+ *  group_is_overloaded is not equals to !group_has_capacity because a group
+ *  with the exact right number of tasks, has no more spare capacity but is not
+ *  overloaded so both group_has_capacity and group_is_overloaded return
+ *  false.
+ */
+static inline bool
+group_is_overloaded(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
+{
+	if (sgs->sum_nr_running <= sgs->group_weight)
+		return false;
+
+	if ((sgs->group_capacity * 100) <
+			(sgs->group_util * imbalance_pct))
+		return true;
+
+	if ((sgs->group_capacity * imbalance_pct) <
+			(sgs->group_runnable * 100))
+		return true;
+
+	return false;
+}
+
+static inline enum
+group_type group_classify(unsigned int imbalance_pct,
+			  struct sched_group *group,
+			  struct sg_lb_stats *sgs)
+{
+	if (group_is_overloaded(imbalance_pct, sgs))
+		return group_overloaded;
+
+	if (sg_imbalanced(group))
+		return group_imbalanced;
+
+	if (sgs->group_asym_packing)
+		return group_asym_packing;
+
+	if (sgs->group_smt_balance)
+		return group_smt_balance;
+
+	if (sgs->group_misfit_task_load)
+		return group_misfit_task;
+
+	if (!group_has_capacity(imbalance_pct, sgs))
+		return group_fully_busy;
+
+	return group_has_spare;
+}
+
+/**
+ * sched_use_asym_prio - Check whether asym_packing priority must be used
+ * @sd:		The scheduling domain of the load balancing
+ * @cpu:	A CPU
+ *
+ * Always use CPU priority when balancing load between SMT siblings. When
+ * balancing load between cores, it is not sufficient that @cpu is idle. Only
+ * use CPU priority if the whole core is idle.
+ *
+ * Returns: True if the priority of @cpu must be followed. False otherwise.
+ */
+static bool sched_use_asym_prio(struct sched_domain *sd, int cpu)
+{
+	if (!(sd->flags & SD_ASYM_PACKING))
+		return false;
+
+	if (!sched_smt_active())
+		return true;
+
+	return sd->flags & SD_SHARE_CPUCAPACITY || is_core_idle(cpu);
+}
+
+static inline bool sched_asym(struct sched_domain *sd, int dst_cpu, int src_cpu)
+{
+	/*
+	 * First check if @dst_cpu can do asym_packing load balance. Only do it
+	 * if it has higher priority than @src_cpu.
+	 */
+	return sched_use_asym_prio(sd, dst_cpu) &&
+		sched_asym_prefer(dst_cpu, src_cpu);
+}
+
+/**
+ * sched_group_asym - Check if the destination CPU can do asym_packing balance
+ * @env:	The load balancing environment
+ * @sgs:	Load-balancing statistics of the candidate busiest group
+ * @group:	The candidate busiest group
+ *
+ * @env::dst_cpu can do asym_packing if it has higher priority than the
+ * preferred CPU of @group.
+ *
+ * Return: true if @env::dst_cpu can do with asym_packing load balance. False
+ * otherwise.
+ */
+static inline bool
+sched_group_asym(struct lb_env *env, struct sg_lb_stats *sgs, struct sched_group *group)
+{
+	/*
+	 * CPU priorities do not make sense for SMT cores with more than one
+	 * busy sibling.
+	 */
+	if ((group->flags & SD_SHARE_CPUCAPACITY) &&
+	    (sgs->group_weight - sgs->idle_cpus != 1))
+		return false;
+
+	return sched_asym(env->sd, env->dst_cpu, group->asym_prefer_cpu);
+}
+
+/* One group has more than one SMT CPU while the other group does not */
+static inline bool smt_vs_nonsmt_groups(struct sched_group *sg1,
+				    struct sched_group *sg2)
+{
+	if (!sg1 || !sg2)
+		return false;
+
+	return (sg1->flags & SD_SHARE_CPUCAPACITY) !=
+		(sg2->flags & SD_SHARE_CPUCAPACITY);
+}
+
+static inline bool smt_balance(struct lb_env *env, struct sg_lb_stats *sgs,
+			       struct sched_group *group)
+{
+	if (!env->idle)
+		return false;
+
+	/*
+	 * For SMT source group, it is better to move a task
+	 * to a CPU that doesn't have multiple tasks sharing its CPU capacity.
+	 * Note that if a group has a single SMT, SD_SHARE_CPUCAPACITY
+	 * will not be on.
+	 */
+	if (group->flags & SD_SHARE_CPUCAPACITY &&
+	    sgs->sum_h_nr_running > 1)
+		return true;
+
+	return false;
+}
+
+static inline long sibling_imbalance(struct lb_env *env,
+				    struct sd_lb_stats *sds,
+				    struct sg_lb_stats *busiest,
+				    struct sg_lb_stats *local)
+{
+	int ncores_busiest, ncores_local;
+	long imbalance;
+
+	if (!env->idle || !busiest->sum_nr_running)
+		return 0;
+
+	ncores_busiest = sds->busiest->cores;
+	ncores_local = sds->local->cores;
+
+	if (ncores_busiest == ncores_local) {
+		imbalance = busiest->sum_nr_running;
+		lsub_positive(&imbalance, local->sum_nr_running);
+		return imbalance;
+	}
+
+	/* Balance such that nr_running/ncores ratio are same on both groups */
+	imbalance = ncores_local * busiest->sum_nr_running;
+	lsub_positive(&imbalance, ncores_busiest * local->sum_nr_running);
+	/* Normalize imbalance and do rounding on normalization */
+	imbalance = 2 * imbalance + ncores_local + ncores_busiest;
+	imbalance /= ncores_local + ncores_busiest;
+
+	/* Take advantage of resource in an empty sched group */
+	if (imbalance <= 1 && local->sum_nr_running == 0 &&
+	    busiest->sum_nr_running > 1)
+		imbalance = 2;
+
+	return imbalance;
+}
+
+static inline bool
+sched_reduced_capacity(struct rq *rq, struct sched_domain *sd)
+{
+	/*
+	 * When there is more than 1 task, the group_overloaded case already
+	 * takes care of cpu with reduced capacity
+	 */
+	if (rq->cfs.h_nr_running != 1)
+		return false;
+
+	return check_cpu_capacity(rq, sd);
+}
+
+/**
+ * update_sg_lb_stats - Update sched_group's statistics for load balancing.
+ * @env: The load balancing environment.
+ * @sds: Load-balancing data with statistics of the local group.
+ * @group: sched_group whose statistics are to be updated.
+ * @sgs: variable to hold the statistics for this group.
+ * @sg_overloaded: sched_group is overloaded
+ * @sg_overutilized: sched_group is overutilized
+ */
+static inline void update_sg_lb_stats(struct lb_env *env,
+				      struct sd_lb_stats *sds,
+				      struct sched_group *group,
+				      struct sg_lb_stats *sgs,
+				      bool *sg_overloaded,
+				      bool *sg_overutilized)
+{
+	int i, nr_running, local_group;
+
+	memset(sgs, 0, sizeof(*sgs));
+
+	local_group = group == sds->local;
+
+	for_each_cpu_and(i, sched_group_span(group), env->cpus) {
+		struct rq *rq = cpu_rq(i);
+		unsigned long load = cpu_load(rq);
+
+		sgs->group_load += load;
+		sgs->group_util += cpu_util_cfs(i);
+		sgs->group_runnable += cpu_runnable(rq);
+		sgs->sum_h_nr_running += rq->cfs.h_nr_running;
+
+		nr_running = rq->nr_running;
+		sgs->sum_nr_running += nr_running;
+
+		if (nr_running > 1)
+			*sg_overloaded = 1;
+
+		if (cpu_overutilized(i))
+			*sg_overutilized = 1;
+
+#ifdef CONFIG_NUMA_BALANCING
+		sgs->nr_numa_running += rq->nr_numa_running;
+		sgs->nr_preferred_running += rq->nr_preferred_running;
+#endif
+		/*
+		 * No need to call idle_cpu() if nr_running is not 0
+		 */
+		if (!nr_running && idle_cpu(i)) {
+			sgs->idle_cpus++;
+			/* Idle cpu can't have misfit task */
+			continue;
+		}
+
+		if (local_group)
+			continue;
+
+		if (env->sd->flags & SD_ASYM_CPUCAPACITY) {
+			/* Check for a misfit task on the cpu */
+			if (sgs->group_misfit_task_load < rq->misfit_task_load) {
+				sgs->group_misfit_task_load = rq->misfit_task_load;
+				*sg_overloaded = 1;
+			}
+		} else if (env->idle && sched_reduced_capacity(rq, env->sd)) {
+			/* Check for a task running on a CPU with reduced capacity */
+			if (sgs->group_misfit_task_load < load)
+				sgs->group_misfit_task_load = load;
+		}
+	}
+
+	sgs->group_capacity = group->sgc->capacity;
+
+	sgs->group_weight = group->group_weight;
+
+	/* Check if dst CPU is idle and preferred to this group */
+	if (!local_group && env->idle && sgs->sum_h_nr_running &&
+	    sched_group_asym(env, sgs, group))
+		sgs->group_asym_packing = 1;
+
+	/* Check for loaded SMT group to be balanced to dst CPU */
+	if (!local_group && smt_balance(env, sgs, group))
+		sgs->group_smt_balance = 1;
+
+	sgs->group_type = group_classify(env->sd->imbalance_pct, group, sgs);
+
+	/* Computing avg_load makes sense only when group is overloaded */
+	if (sgs->group_type == group_overloaded)
+		sgs->avg_load = (sgs->group_load * SCHED_CAPACITY_SCALE) /
+				sgs->group_capacity;
+}
+
+/**
+ * update_sd_pick_busiest - return 1 on busiest group
+ * @env: The load balancing environment.
+ * @sds: sched_domain statistics
+ * @sg: sched_group candidate to be checked for being the busiest
+ * @sgs: sched_group statistics
+ *
+ * Determine if @sg is a busier group than the previously selected
+ * busiest group.
+ *
+ * Return: %true if @sg is a busier group than the previously selected
+ * busiest group. %false otherwise.
+ */
+static bool update_sd_pick_busiest(struct lb_env *env,
+				   struct sd_lb_stats *sds,
+				   struct sched_group *sg,
+				   struct sg_lb_stats *sgs)
+{
+	struct sg_lb_stats *busiest = &sds->busiest_stat;
+
+	/* Make sure that there is at least one task to pull */
+	if (!sgs->sum_h_nr_running)
+		return false;
+
+	/*
+	 * Don't try to pull misfit tasks we can't help.
+	 * We can use max_capacity here as reduction in capacity on some
+	 * CPUs in the group should either be possible to resolve
+	 * internally or be covered by avg_load imbalance (eventually).
+	 */
+	if ((env->sd->flags & SD_ASYM_CPUCAPACITY) &&
+	    (sgs->group_type == group_misfit_task) &&
+	    (!capacity_greater(capacity_of(env->dst_cpu), sg->sgc->max_capacity) ||
+	     sds->local_stat.group_type != group_has_spare))
+		return false;
+
+	if (sgs->group_type > busiest->group_type)
+		return true;
+
+	if (sgs->group_type < busiest->group_type)
+		return false;
+
+	/*
+	 * The candidate and the current busiest group are the same type of
+	 * group. Let check which one is the busiest according to the type.
+	 */
+
+	switch (sgs->group_type) {
+	case group_overloaded:
+		/* Select the overloaded group with highest avg_load. */
+		return sgs->avg_load > busiest->avg_load;
+
+	case group_imbalanced:
+		/*
+		 * Select the 1st imbalanced group as we don't have any way to
+		 * choose one more than another.
+		 */
+		return false;
+
+	case group_asym_packing:
+		/* Prefer to move from lowest priority CPU's work */
+		return sched_asym_prefer(sds->busiest->asym_prefer_cpu, sg->asym_prefer_cpu);
+
+	case group_misfit_task:
+		/*
+		 * If we have more than one misfit sg go with the biggest
+		 * misfit.
+		 */
+		return sgs->group_misfit_task_load > busiest->group_misfit_task_load;
+
+	case group_smt_balance:
+		/*
+		 * Check if we have spare CPUs on either SMT group to
+		 * choose has spare or fully busy handling.
+		 */
+		if (sgs->idle_cpus != 0 || busiest->idle_cpus != 0)
+			goto has_spare;
+
+		fallthrough;
+
+	case group_fully_busy:
+		/*
+		 * Select the fully busy group with highest avg_load. In
+		 * theory, there is no need to pull task from such kind of
+		 * group because tasks have all compute capacity that they need
+		 * but we can still improve the overall throughput by reducing
+		 * contention when accessing shared HW resources.
+		 *
+		 * XXX for now avg_load is not computed and always 0 so we
+		 * select the 1st one, except if @sg is composed of SMT
+		 * siblings.
+		 */
+
+		if (sgs->avg_load < busiest->avg_load)
+			return false;
+
+		if (sgs->avg_load == busiest->avg_load) {
+			/*
+			 * SMT sched groups need more help than non-SMT groups.
+			 * If @sg happens to also be SMT, either choice is good.
+			 */
+			if (sds->busiest->flags & SD_SHARE_CPUCAPACITY)
+				return false;
+		}
+
+		break;
+
+	case group_has_spare:
+		/*
+		 * Do not pick sg with SMT CPUs over sg with pure CPUs,
+		 * as we do not want to pull task off SMT core with one task
+		 * and make the core idle.
+		 */
+		if (smt_vs_nonsmt_groups(sds->busiest, sg)) {
+			if (sg->flags & SD_SHARE_CPUCAPACITY && sgs->sum_h_nr_running <= 1)
+				return false;
+			else
+				return true;
+		}
+has_spare:
+
+		/*
+		 * Select not overloaded group with lowest number of idle CPUs
+		 * and highest number of running tasks. We could also compare
+		 * the spare capacity which is more stable but it can end up
+		 * that the group has less spare capacity but finally more idle
+		 * CPUs which means less opportunity to pull tasks.
+		 */
+		if (sgs->idle_cpus > busiest->idle_cpus)
+			return false;
+		else if ((sgs->idle_cpus == busiest->idle_cpus) &&
+			 (sgs->sum_nr_running <= busiest->sum_nr_running))
+			return false;
+
+		break;
+	}
+
+	/*
+	 * Candidate sg has no more than one task per CPU and has higher
+	 * per-CPU capacity. Migrating tasks to less capable CPUs may harm
+	 * throughput. Maximize throughput, power/energy consequences are not
+	 * considered.
+	 */
+	if ((env->sd->flags & SD_ASYM_CPUCAPACITY) &&
+	    (sgs->group_type <= group_fully_busy) &&
+	    (capacity_greater(sg->sgc->min_capacity, capacity_of(env->dst_cpu))))
+		return false;
+
+	return true;
+}
+
+#ifdef CONFIG_NUMA_BALANCING
+static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs)
+{
+	if (sgs->sum_h_nr_running > sgs->nr_numa_running)
+		return regular;
+	if (sgs->sum_h_nr_running > sgs->nr_preferred_running)
+		return remote;
+	return all;
+}
+
+static inline enum fbq_type fbq_classify_rq(struct rq *rq)
+{
+	if (rq->nr_running > rq->nr_numa_running)
+		return regular;
+	if (rq->nr_running > rq->nr_preferred_running)
+		return remote;
+	return all;
+}
+#else
+static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs)
+{
+	return all;
+}
+
+static inline enum fbq_type fbq_classify_rq(struct rq *rq)
+{
+	return regular;
+}
+#endif /* CONFIG_NUMA_BALANCING */
+
+
+struct sg_lb_stats;
+
+/*
+ * task_running_on_cpu - return 1 if @p is running on @cpu.
+ */
+
+static unsigned int task_running_on_cpu(int cpu, struct task_struct *p)
+{
+	/* Task has no contribution or is new */
+	if (cpu != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
+		return 0;
+
+	if (task_on_rq_queued(p))
+		return 1;
+
+	return 0;
+}
+
+/**
+ * idle_cpu_without - would a given CPU be idle without p ?
+ * @cpu: the processor on which idleness is tested.
+ * @p: task which should be ignored.
+ *
+ * Return: 1 if the CPU would be idle. 0 otherwise.
+ */
+static int idle_cpu_without(int cpu, struct task_struct *p)
+{
+	struct rq *rq = cpu_rq(cpu);
+
+	if (rq->curr != rq->idle && rq->curr != p)
+		return 0;
+
+	/*
+	 * rq->nr_running can't be used but an updated version without the
+	 * impact of p on cpu must be used instead. The updated nr_running
+	 * be computed and tested before calling idle_cpu_without().
+	 */
+
+	if (rq->ttwu_pending)
+		return 0;
+
+	return 1;
+}
+
+/*
+ * update_sg_wakeup_stats - Update sched_group's statistics for wakeup.
+ * @sd: The sched_domain level to look for idlest group.
+ * @group: sched_group whose statistics are to be updated.
+ * @sgs: variable to hold the statistics for this group.
+ * @p: The task for which we look for the idlest group/CPU.
+ */
+static inline void update_sg_wakeup_stats(struct sched_domain *sd,
+					  struct sched_group *group,
+					  struct sg_lb_stats *sgs,
+					  struct task_struct *p)
+{
+	int i, nr_running;
+
+	memset(sgs, 0, sizeof(*sgs));
+
+	/* Assume that task can't fit any CPU of the group */
+	if (sd->flags & SD_ASYM_CPUCAPACITY)
+		sgs->group_misfit_task_load = 1;
+
+	for_each_cpu(i, sched_group_span(group)) {
+		struct rq *rq = cpu_rq(i);
+		unsigned int local;
+
+		sgs->group_load += cpu_load_without(rq, p);
+		sgs->group_util += cpu_util_without(i, p);
+		sgs->group_runnable += cpu_runnable_without(rq, p);
+		local = task_running_on_cpu(i, p);
+		sgs->sum_h_nr_running += rq->cfs.h_nr_running - local;
+
+		nr_running = rq->nr_running - local;
+		sgs->sum_nr_running += nr_running;
+
+		/*
+		 * No need to call idle_cpu_without() if nr_running is not 0
+		 */
+		if (!nr_running && idle_cpu_without(i, p))
+			sgs->idle_cpus++;
+
+		/* Check if task fits in the CPU */
+		if (sd->flags & SD_ASYM_CPUCAPACITY &&
+		    sgs->group_misfit_task_load &&
+		    task_fits_cpu(p, i))
+			sgs->group_misfit_task_load = 0;
+
+	}
+
+	sgs->group_capacity = group->sgc->capacity;
+
+	sgs->group_weight = group->group_weight;
+
+	sgs->group_type = group_classify(sd->imbalance_pct, group, sgs);
+
+	/*
+	 * Computing avg_load makes sense only when group is fully busy or
+	 * overloaded
+	 */
+	if (sgs->group_type == group_fully_busy ||
+		sgs->group_type == group_overloaded)
+		sgs->avg_load = (sgs->group_load * SCHED_CAPACITY_SCALE) /
+				sgs->group_capacity;
+}
+
+static bool update_pick_idlest(struct sched_group *idlest,
+			       struct sg_lb_stats *idlest_sgs,
+			       struct sched_group *group,
+			       struct sg_lb_stats *sgs)
+{
+	if (sgs->group_type < idlest_sgs->group_type)
+		return true;
+
+	if (sgs->group_type > idlest_sgs->group_type)
+		return false;
+
+	/*
+	 * The candidate and the current idlest group are the same type of
+	 * group. Let check which one is the idlest according to the type.
+	 */
+
+	switch (sgs->group_type) {
+	case group_overloaded:
+	case group_fully_busy:
+		/* Select the group with lowest avg_load. */
+		if (idlest_sgs->avg_load <= sgs->avg_load)
+			return false;
+		break;
+
+	case group_imbalanced:
+	case group_asym_packing:
+	case group_smt_balance:
+		/* Those types are not used in the slow wakeup path */
+		return false;
+
+	case group_misfit_task:
+		/* Select group with the highest max capacity */
+		if (idlest->sgc->max_capacity >= group->sgc->max_capacity)
+			return false;
+		break;
+
+	case group_has_spare:
+		/* Select group with most idle CPUs */
+		if (idlest_sgs->idle_cpus > sgs->idle_cpus)
+			return false;
+
+		/* Select group with lowest group_util */
+		if (idlest_sgs->idle_cpus == sgs->idle_cpus &&
+			idlest_sgs->group_util <= sgs->group_util)
+			return false;
+
+		break;
+	}
+
+	return true;
+}
+
+/*
+ * sched_balance_find_dst_group() finds and returns the least busy CPU group within the
+ * domain.
+ *
+ * Assumes p is allowed on at least one CPU in sd.
+ */
+struct sched_group *
+sched_balance_find_dst_group(struct sched_domain *sd, struct task_struct *p, int this_cpu)
+{
+	struct sched_group *idlest = NULL, *local = NULL, *group = sd->groups;
+	struct sg_lb_stats local_sgs, tmp_sgs;
+	struct sg_lb_stats *sgs;
+	unsigned long imbalance;
+	struct sg_lb_stats idlest_sgs = {
+			.avg_load = UINT_MAX,
+			.group_type = group_overloaded,
+	};
+
+	do {
+		int local_group;
+
+		/* Skip over this group if it has no CPUs allowed */
+		if (!cpumask_intersects(sched_group_span(group),
+					p->cpus_ptr))
+			continue;
+
+		/* Skip over this group if no cookie matched */
+		if (!sched_group_cookie_match(cpu_rq(this_cpu), p, group))
+			continue;
+
+		local_group = cpumask_test_cpu(this_cpu,
+					       sched_group_span(group));
+
+		if (local_group) {
+			sgs = &local_sgs;
+			local = group;
+		} else {
+			sgs = &tmp_sgs;
+		}
+
+		update_sg_wakeup_stats(sd, group, sgs, p);
+
+		if (!local_group && update_pick_idlest(idlest, &idlest_sgs, group, sgs)) {
+			idlest = group;
+			idlest_sgs = *sgs;
+		}
+
+	} while (group = group->next, group != sd->groups);
+
+
+	/* There is no idlest group to push tasks to */
+	if (!idlest)
+		return NULL;
+
+	/* The local group has been skipped because of CPU affinity */
+	if (!local)
+		return idlest;
+
+	/*
+	 * If the local group is idler than the selected idlest group
+	 * don't try and push the task.
+	 */
+	if (local_sgs.group_type < idlest_sgs.group_type)
+		return NULL;
+
+	/*
+	 * If the local group is busier than the selected idlest group
+	 * try and push the task.
+	 */
+	if (local_sgs.group_type > idlest_sgs.group_type)
+		return idlest;
+
+	switch (local_sgs.group_type) {
+	case group_overloaded:
+	case group_fully_busy:
+
+		/* Calculate allowed imbalance based on load */
+		imbalance = scale_load_down(NICE_0_LOAD) *
+				(sd->imbalance_pct-100) / 100;
+
+		/*
+		 * When comparing groups across NUMA domains, it's possible for
+		 * the local domain to be very lightly loaded relative to the
+		 * remote domains but "imbalance" skews the comparison making
+		 * remote CPUs look much more favourable. When considering
+		 * cross-domain, add imbalance to the load on the remote node
+		 * and consider staying local.
+		 */
+
+		if ((sd->flags & SD_NUMA) &&
+		    ((idlest_sgs.avg_load + imbalance) >= local_sgs.avg_load))
+			return NULL;
+
+		/*
+		 * If the local group is less loaded than the selected
+		 * idlest group don't try and push any tasks.
+		 */
+		if (idlest_sgs.avg_load >= (local_sgs.avg_load + imbalance))
+			return NULL;
+
+		if (100 * local_sgs.avg_load <= sd->imbalance_pct * idlest_sgs.avg_load)
+			return NULL;
+		break;
+
+	case group_imbalanced:
+	case group_asym_packing:
+	case group_smt_balance:
+		/* Those type are not used in the slow wakeup path */
+		return NULL;
+
+	case group_misfit_task:
+		/* Select group with the highest max capacity */
+		if (local->sgc->max_capacity >= idlest->sgc->max_capacity)
+			return NULL;
+		break;
+
+	case group_has_spare:
+#ifdef CONFIG_NUMA
+		if (sd->flags & SD_NUMA) {
+			int imb_numa_nr = sd->imb_numa_nr;
+#ifdef CONFIG_NUMA_BALANCING
+			int idlest_cpu;
+			/*
+			 * If there is spare capacity at NUMA, try to select
+			 * the preferred node
+			 */
+			if (cpu_to_node(this_cpu) == p->numa_preferred_nid)
+				return NULL;
+
+			idlest_cpu = cpumask_first(sched_group_span(idlest));
+			if (cpu_to_node(idlest_cpu) == p->numa_preferred_nid)
+				return idlest;
+#endif /* CONFIG_NUMA_BALANCING */
+			/*
+			 * Otherwise, keep the task close to the wakeup source
+			 * and improve locality if the number of running tasks
+			 * would remain below threshold where an imbalance is
+			 * allowed while accounting for the possibility the
+			 * task is pinned to a subset of CPUs. If there is a
+			 * real need of migration, periodic load balance will
+			 * take care of it.
+			 */
+			if (p->nr_cpus_allowed != NR_CPUS) {
+				struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_rq_mask);
+
+				cpumask_and(cpus, sched_group_span(local), p->cpus_ptr);
+				imb_numa_nr = min(cpumask_weight(cpus), sd->imb_numa_nr);
+			}
+
+			imbalance = abs(local_sgs.idle_cpus - idlest_sgs.idle_cpus);
+			if (!adjust_numa_imbalance(imbalance,
+						   local_sgs.sum_nr_running + 1,
+						   imb_numa_nr)) {
+				return NULL;
+			}
+		}
+#endif /* CONFIG_NUMA */
+
+		/*
+		 * Select group with highest number of idle CPUs. We could also
+		 * compare the utilization which is more stable but it can end
+		 * up that the group has less spare capacity but finally more
+		 * idle CPUs which means more opportunity to run task.
+		 */
+		if (local_sgs.idle_cpus >= idlest_sgs.idle_cpus)
+			return NULL;
+		break;
+	}
+
+	return idlest;
+}
+
+static void update_idle_cpu_scan(struct lb_env *env,
+				 unsigned long sum_util)
+{
+	struct sched_domain_shared *sd_share;
+	int llc_weight, pct;
+	u64 x, y, tmp;
+	/*
+	 * Update the number of CPUs to scan in LLC domain, which could
+	 * be used as a hint in select_idle_cpu(). The update of sd_share
+	 * could be expensive because it is within a shared cache line.
+	 * So the write of this hint only occurs during periodic load
+	 * balancing, rather than CPU_NEWLY_IDLE, because the latter
+	 * can fire way more frequently than the former.
+	 */
+	if (!sched_feat(SIS_UTIL) || env->idle == CPU_NEWLY_IDLE)
+		return;
+
+	llc_weight = per_cpu(sd_llc_size, env->dst_cpu);
+	if (env->sd->span_weight != llc_weight)
+		return;
+
+	sd_share = rcu_dereference(per_cpu(sd_llc_shared, env->dst_cpu));
+	if (!sd_share)
+		return;
+
+	/*
+	 * The number of CPUs to search drops as sum_util increases, when
+	 * sum_util hits 85% or above, the scan stops.
+	 * The reason to choose 85% as the threshold is because this is the
+	 * imbalance_pct(117) when a LLC sched group is overloaded.
+	 *
+	 * let y = SCHED_CAPACITY_SCALE - p * x^2                       [1]
+	 * and y'= y / SCHED_CAPACITY_SCALE
+	 *
+	 * x is the ratio of sum_util compared to the CPU capacity:
+	 * x = sum_util / (llc_weight * SCHED_CAPACITY_SCALE)
+	 * y' is the ratio of CPUs to be scanned in the LLC domain,
+	 * and the number of CPUs to scan is calculated by:
+	 *
+	 * nr_scan = llc_weight * y'                                    [2]
+	 *
+	 * When x hits the threshold of overloaded, AKA, when
+	 * x = 100 / pct, y drops to 0. According to [1],
+	 * p should be SCHED_CAPACITY_SCALE * pct^2 / 10000
+	 *
+	 * Scale x by SCHED_CAPACITY_SCALE:
+	 * x' = sum_util / llc_weight;                                  [3]
+	 *
+	 * and finally [1] becomes:
+	 * y = SCHED_CAPACITY_SCALE -
+	 *     x'^2 * pct^2 / (10000 * SCHED_CAPACITY_SCALE)            [4]
+	 *
+	 */
+	/* equation [3] */
+	x = sum_util;
+	do_div(x, llc_weight);
+
+	/* equation [4] */
+	pct = env->sd->imbalance_pct;
+	tmp = x * x * pct * pct;
+	do_div(tmp, 10000 * SCHED_CAPACITY_SCALE);
+	tmp = min_t(long, tmp, SCHED_CAPACITY_SCALE);
+	y = SCHED_CAPACITY_SCALE - tmp;
+
+	/* equation [2] */
+	y *= llc_weight;
+	do_div(y, SCHED_CAPACITY_SCALE);
+	if ((int)y != sd_share->nr_idle_scan)
+		WRITE_ONCE(sd_share->nr_idle_scan, (int)y);
+}
+
+/**
+ * update_sd_lb_stats - Update sched_domain's statistics for load balancing.
+ * @env: The load balancing environment.
+ * @sds: variable to hold the statistics for this sched_domain.
+ */
+
+static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sds)
+{
+	struct sched_group *sg = env->sd->groups;
+	struct sg_lb_stats *local = &sds->local_stat;
+	struct sg_lb_stats tmp_sgs;
+	unsigned long sum_util = 0;
+	bool sg_overloaded = 0, sg_overutilized = 0;
+
+	do {
+		struct sg_lb_stats *sgs = &tmp_sgs;
+		int local_group;
+
+		local_group = cpumask_test_cpu(env->dst_cpu, sched_group_span(sg));
+		if (local_group) {
+			sds->local = sg;
+			sgs = local;
+
+			if (env->idle != CPU_NEWLY_IDLE ||
+			    time_after_eq(jiffies, sg->sgc->next_update))
+				update_group_capacity(env->sd, env->dst_cpu);
+		}
+
+		update_sg_lb_stats(env, sds, sg, sgs, &sg_overloaded, &sg_overutilized);
+
+		if (!local_group && update_sd_pick_busiest(env, sds, sg, sgs)) {
+			sds->busiest = sg;
+			sds->busiest_stat = *sgs;
+		}
+
+		/* Now, start updating sd_lb_stats */
+		sds->total_load += sgs->group_load;
+		sds->total_capacity += sgs->group_capacity;
+
+		sum_util += sgs->group_util;
+		sg = sg->next;
+	} while (sg != env->sd->groups);
+
+	/*
+	 * Indicate that the child domain of the busiest group prefers tasks
+	 * go to a child's sibling domains first. NB the flags of a sched group
+	 * are those of the child domain.
+	 */
+	if (sds->busiest)
+		sds->prefer_sibling = !!(sds->busiest->flags & SD_PREFER_SIBLING);
+
+
+	if (env->sd->flags & SD_NUMA)
+		env->fbq_type = fbq_classify_group(&sds->busiest_stat);
+
+	if (!env->sd->parent) {
+		/* update overload indicator if we are at root domain */
+		set_rd_overloaded(env->dst_rq->rd, sg_overloaded);
+
+		/* Update over-utilization (tipping point, U >= 0) indicator */
+		set_rd_overutilized(env->dst_rq->rd, sg_overloaded);
+	} else if (sg_overutilized) {
+		set_rd_overutilized(env->dst_rq->rd, sg_overutilized);
+	}
+
+	update_idle_cpu_scan(env, sum_util);
+}
+
+/**
+ * calculate_imbalance - Calculate the amount of imbalance present within the
+ *			 groups of a given sched_domain during load balance.
+ * @env: load balance environment
+ * @sds: statistics of the sched_domain whose imbalance is to be calculated.
+ */
+static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
+{
+	struct sg_lb_stats *local, *busiest;
+
+	local = &sds->local_stat;
+	busiest = &sds->busiest_stat;
+
+	if (busiest->group_type == group_misfit_task) {
+		if (env->sd->flags & SD_ASYM_CPUCAPACITY) {
+			/* Set imbalance to allow misfit tasks to be balanced. */
+			env->migration_type = migrate_misfit;
+			env->imbalance = 1;
+		} else {
+			/*
+			 * Set load imbalance to allow moving task from cpu
+			 * with reduced capacity.
+			 */
+			env->migration_type = migrate_load;
+			env->imbalance = busiest->group_misfit_task_load;
+		}
+		return;
+	}
+
+	if (busiest->group_type == group_asym_packing) {
+		/*
+		 * In case of asym capacity, we will try to migrate all load to
+		 * the preferred CPU.
+		 */
+		env->migration_type = migrate_task;
+		env->imbalance = busiest->sum_h_nr_running;
+		return;
+	}
+
+	if (busiest->group_type == group_smt_balance) {
+		/* Reduce number of tasks sharing CPU capacity */
+		env->migration_type = migrate_task;
+		env->imbalance = 1;
+		return;
+	}
+
+	if (busiest->group_type == group_imbalanced) {
+		/*
+		 * In the group_imb case we cannot rely on group-wide averages
+		 * to ensure CPU-load equilibrium, try to move any task to fix
+		 * the imbalance. The next load balance will take care of
+		 * balancing back the system.
+		 */
+		env->migration_type = migrate_task;
+		env->imbalance = 1;
+		return;
+	}
+
+	/*
+	 * Try to use spare capacity of local group without overloading it or
+	 * emptying busiest.
+	 */
+	if (local->group_type == group_has_spare) {
+		if ((busiest->group_type > group_fully_busy) &&
+		    !(env->sd->flags & SD_SHARE_LLC)) {
+			/*
+			 * If busiest is overloaded, try to fill spare
+			 * capacity. This might end up creating spare capacity
+			 * in busiest or busiest still being overloaded but
+			 * there is no simple way to directly compute the
+			 * amount of load to migrate in order to balance the
+			 * system.
+			 */
+			env->migration_type = migrate_util;
+			env->imbalance = max(local->group_capacity, local->group_util) -
+					 local->group_util;
+
+			/*
+			 * In some cases, the group's utilization is max or even
+			 * higher than capacity because of migrations but the
+			 * local CPU is (newly) idle. There is at least one
+			 * waiting task in this overloaded busiest group. Let's
+			 * try to pull it.
+			 */
+			if (env->idle && env->imbalance == 0) {
+				env->migration_type = migrate_task;
+				env->imbalance = 1;
+			}
+
+			return;
+		}
+
+		if (busiest->group_weight == 1 || sds->prefer_sibling) {
+			/*
+			 * When prefer sibling, evenly spread running tasks on
+			 * groups.
+			 */
+			env->migration_type = migrate_task;
+			env->imbalance = sibling_imbalance(env, sds, busiest, local);
+		} else {
+
+			/*
+			 * If there is no overload, we just want to even the number of
+			 * idle CPUs.
+			 */
+			env->migration_type = migrate_task;
+			env->imbalance = max_t(long, 0,
+					       (local->idle_cpus - busiest->idle_cpus));
+		}
+
+#ifdef CONFIG_NUMA
+		/* Consider allowing a small imbalance between NUMA groups */
+		if (env->sd->flags & SD_NUMA) {
+			env->imbalance = adjust_numa_imbalance(env->imbalance,
+							       local->sum_nr_running + 1,
+							       env->sd->imb_numa_nr);
+		}
+#endif
+
+		/* Number of tasks to move to restore balance */
+		env->imbalance >>= 1;
+
+		return;
+	}
+
+	/*
+	 * Local is fully busy but has to take more load to relieve the
+	 * busiest group
+	 */
+	if (local->group_type < group_overloaded) {
+		/*
+		 * Local will become overloaded so the avg_load metrics are
+		 * finally needed.
+		 */
+
+		local->avg_load = (local->group_load * SCHED_CAPACITY_SCALE) /
+				  local->group_capacity;
+
+		/*
+		 * If the local group is more loaded than the selected
+		 * busiest group don't try to pull any tasks.
+		 */
+		if (local->avg_load >= busiest->avg_load) {
+			env->imbalance = 0;
+			return;
+		}
+
+		sds->avg_load = (sds->total_load * SCHED_CAPACITY_SCALE) /
+				sds->total_capacity;
+
+		/*
+		 * If the local group is more loaded than the average system
+		 * load, don't try to pull any tasks.
+		 */
+		if (local->avg_load >= sds->avg_load) {
+			env->imbalance = 0;
+			return;
+		}
+
+	}
+
+	/*
+	 * Both group are or will become overloaded and we're trying to get all
+	 * the CPUs to the average_load, so we don't want to push ourselves
+	 * above the average load, nor do we wish to reduce the max loaded CPU
+	 * below the average load. At the same time, we also don't want to
+	 * reduce the group load below the group capacity. Thus we look for
+	 * the minimum possible imbalance.
+	 */
+	env->migration_type = migrate_load;
+	env->imbalance = min(
+		(busiest->avg_load - sds->avg_load) * busiest->group_capacity,
+		(sds->avg_load - local->avg_load) * local->group_capacity
+	) / SCHED_CAPACITY_SCALE;
+}
+
+/******* sched_balance_find_src_group() helpers end here *********************/
+
+/*
+ * Decision matrix according to the local and busiest group type:
+ *
+ * busiest \ local has_spare fully_busy misfit asym imbalanced overloaded
+ * has_spare        nr_idle   balanced   N/A    N/A  balanced   balanced
+ * fully_busy       nr_idle   nr_idle    N/A    N/A  balanced   balanced
+ * misfit_task      force     N/A        N/A    N/A  N/A        N/A
+ * asym_packing     force     force      N/A    N/A  force      force
+ * imbalanced       force     force      N/A    N/A  force      force
+ * overloaded       force     force      N/A    N/A  force      avg_load
+ *
+ * N/A :      Not Applicable because already filtered while updating
+ *            statistics.
+ * balanced : The system is balanced for these 2 groups.
+ * force :    Calculate the imbalance as load migration is probably needed.
+ * avg_load : Only if imbalance is significant enough.
+ * nr_idle :  dst_cpu is not busy and the number of idle CPUs is quite
+ *            different in groups.
+ */
+
+/**
+ * sched_balance_find_src_group - Returns the busiest group within the sched_domain
+ * if there is an imbalance.
+ * @env: The load balancing environment.
+ *
+ * Also calculates the amount of runnable load which should be moved
+ * to restore balance.
+ *
+ * Return:	- The busiest group if imbalance exists.
+ */
+static struct sched_group *sched_balance_find_src_group(struct lb_env *env)
+{
+	struct sg_lb_stats *local, *busiest;
+	struct sd_lb_stats sds;
+
+	init_sd_lb_stats(&sds);
+
+	/*
+	 * Compute the various statistics relevant for load balancing at
+	 * this level.
+	 */
+	update_sd_lb_stats(env, &sds);
+
+	/* There is no busy sibling group to pull tasks from */
+	if (!sds.busiest)
+		goto out_balanced;
+
+	busiest = &sds.busiest_stat;
+
+	/* Misfit tasks should be dealt with regardless of the avg load */
+	if (busiest->group_type == group_misfit_task)
+		goto force_balance;
+
+	if (!is_rd_overutilized(env->dst_rq->rd) &&
+	    rcu_dereference(env->dst_rq->rd->pd))
+		goto out_balanced;
+
+	/* ASYM feature bypasses nice load balance check */
+	if (busiest->group_type == group_asym_packing)
+		goto force_balance;
+
+	/*
+	 * If the busiest group is imbalanced the below checks don't
+	 * work because they assume all things are equal, which typically
+	 * isn't true due to cpus_ptr constraints and the like.
+	 */
+	if (busiest->group_type == group_imbalanced)
+		goto force_balance;
+
+	local = &sds.local_stat;
+	/*
+	 * If the local group is busier than the selected busiest group
+	 * don't try and pull any tasks.
+	 */
+	if (local->group_type > busiest->group_type)
+		goto out_balanced;
+
+	/*
+	 * When groups are overloaded, use the avg_load to ensure fairness
+	 * between tasks.
+	 */
+	if (local->group_type == group_overloaded) {
+		/*
+		 * If the local group is more loaded than the selected
+		 * busiest group don't try to pull any tasks.
+		 */
+		if (local->avg_load >= busiest->avg_load)
+			goto out_balanced;
+
+		/* XXX broken for overlapping NUMA groups */
+		sds.avg_load = (sds.total_load * SCHED_CAPACITY_SCALE) /
+				sds.total_capacity;
+
+		/*
+		 * Don't pull any tasks if this group is already above the
+		 * domain average load.
+		 */
+		if (local->avg_load >= sds.avg_load)
+			goto out_balanced;
+
+		/*
+		 * If the busiest group is more loaded, use imbalance_pct to be
+		 * conservative.
+		 */
+		if (100 * busiest->avg_load <=
+				env->sd->imbalance_pct * local->avg_load)
+			goto out_balanced;
+	}
+
+	/*
+	 * Try to move all excess tasks to a sibling domain of the busiest
+	 * group's child domain.
+	 */
+	if (sds.prefer_sibling && local->group_type == group_has_spare &&
+	    sibling_imbalance(env, &sds, busiest, local) > 1)
+		goto force_balance;
+
+	if (busiest->group_type != group_overloaded) {
+		if (!env->idle) {
+			/*
+			 * If the busiest group is not overloaded (and as a
+			 * result the local one too) but this CPU is already
+			 * busy, let another idle CPU try to pull task.
+			 */
+			goto out_balanced;
+		}
+
+		if (busiest->group_type == group_smt_balance &&
+		    smt_vs_nonsmt_groups(sds.local, sds.busiest)) {
+			/* Let non SMT CPU pull from SMT CPU sharing with sibling */
+			goto force_balance;
+		}
+
+		if (busiest->group_weight > 1 &&
+		    local->idle_cpus <= (busiest->idle_cpus + 1)) {
+			/*
+			 * If the busiest group is not overloaded
+			 * and there is no imbalance between this and busiest
+			 * group wrt idle CPUs, it is balanced. The imbalance
+			 * becomes significant if the diff is greater than 1
+			 * otherwise we might end up to just move the imbalance
+			 * on another group. Of course this applies only if
+			 * there is more than 1 CPU per group.
+			 */
+			goto out_balanced;
+		}
+
+		if (busiest->sum_h_nr_running == 1) {
+			/*
+			 * busiest doesn't have any tasks waiting to run
+			 */
+			goto out_balanced;
+		}
+	}
+
+force_balance:
+	/* Looks like there is an imbalance. Compute it */
+	calculate_imbalance(env, &sds);
+	return env->imbalance ? sds.busiest : NULL;
+
+out_balanced:
+	env->imbalance = 0;
+	return NULL;
+}
+
+/*
+ * sched_balance_find_src_rq - find the busiest runqueue among the CPUs in the group.
+ */
+static struct rq *sched_balance_find_src_rq(struct lb_env *env,
+				     struct sched_group *group)
+{
+	struct rq *busiest = NULL, *rq;
+	unsigned long busiest_util = 0, busiest_load = 0, busiest_capacity = 1;
+	unsigned int busiest_nr = 0;
+	int i;
+
+	for_each_cpu_and(i, sched_group_span(group), env->cpus) {
+		unsigned long capacity, load, util;
+		unsigned int nr_running;
+		enum fbq_type rt;
+
+		rq = cpu_rq(i);
+		rt = fbq_classify_rq(rq);
+
+		/*
+		 * We classify groups/runqueues into three groups:
+		 *  - regular: there are !numa tasks
+		 *  - remote:  there are numa tasks that run on the 'wrong' node
+		 *  - all:     there is no distinction
+		 *
+		 * In order to avoid migrating ideally placed numa tasks,
+		 * ignore those when there's better options.
+		 *
+		 * If we ignore the actual busiest queue to migrate another
+		 * task, the next balance pass can still reduce the busiest
+		 * queue by moving tasks around inside the node.
+		 *
+		 * If we cannot move enough load due to this classification
+		 * the next pass will adjust the group classification and
+		 * allow migration of more tasks.
+		 *
+		 * Both cases only affect the total convergence complexity.
+		 */
+		if (rt > env->fbq_type)
+			continue;
+
+		nr_running = rq->cfs.h_nr_running;
+		if (!nr_running)
+			continue;
+
+		capacity = capacity_of(i);
+
+		/*
+		 * For ASYM_CPUCAPACITY domains, don't pick a CPU that could
+		 * eventually lead to active_balancing high->low capacity.
+		 * Higher per-CPU capacity is considered better than balancing
+		 * average load.
+		 */
+		if (env->sd->flags & SD_ASYM_CPUCAPACITY &&
+		    !capacity_greater(capacity_of(env->dst_cpu), capacity) &&
+		    nr_running == 1)
+			continue;
+
+		/*
+		 * Make sure we only pull tasks from a CPU of lower priority
+		 * when balancing between SMT siblings.
+		 *
+		 * If balancing between cores, let lower priority CPUs help
+		 * SMT cores with more than one busy sibling.
+		 */
+		if (sched_asym(env->sd, i, env->dst_cpu) && nr_running == 1)
+			continue;
+
+		switch (env->migration_type) {
+		case migrate_load:
+			/*
+			 * When comparing with load imbalance, use cpu_load()
+			 * which is not scaled with the CPU capacity.
+			 */
+			load = cpu_load(rq);
+
+			if (nr_running == 1 && load > env->imbalance &&
+			    !check_cpu_capacity(rq, env->sd))
+				break;
+
+			/*
+			 * For the load comparisons with the other CPUs,
+			 * consider the cpu_load() scaled with the CPU
+			 * capacity, so that the load can be moved away
+			 * from the CPU that is potentially running at a
+			 * lower capacity.
+			 *
+			 * Thus we're looking for max(load_i / capacity_i),
+			 * crosswise multiplication to rid ourselves of the
+			 * division works out to:
+			 * load_i * capacity_j > load_j * capacity_i;
+			 * where j is our previous maximum.
+			 */
+			if (load * busiest_capacity > busiest_load * capacity) {
+				busiest_load = load;
+				busiest_capacity = capacity;
+				busiest = rq;
+			}
+			break;
+
+		case migrate_util:
+			util = cpu_util_cfs_boost(i);
+
+			/*
+			 * Don't try to pull utilization from a CPU with one
+			 * running task. Whatever its utilization, we will fail
+			 * detach the task.
+			 */
+			if (nr_running <= 1)
+				continue;
+
+			if (busiest_util < util) {
+				busiest_util = util;
+				busiest = rq;
+			}
+			break;
+
+		case migrate_task:
+			if (busiest_nr < nr_running) {
+				busiest_nr = nr_running;
+				busiest = rq;
+			}
+			break;
+
+		case migrate_misfit:
+			/*
+			 * For ASYM_CPUCAPACITY domains with misfit tasks we
+			 * simply seek the "biggest" misfit task.
+			 */
+			if (rq->misfit_task_load > busiest_load) {
+				busiest_load = rq->misfit_task_load;
+				busiest = rq;
+			}
+
+			break;
+
+		}
+	}
+
+	return busiest;
+}
+
+/*
+ * Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
+ * so long as it is large enough.
+ */
+#define MAX_PINNED_INTERVAL	512
+
+static inline bool
+asym_active_balance(struct lb_env *env)
+{
+	/*
+	 * ASYM_PACKING needs to force migrate tasks from busy but lower
+	 * priority CPUs in order to pack all tasks in the highest priority
+	 * CPUs. When done between cores, do it only if the whole core if the
+	 * whole core is idle.
+	 *
+	 * If @env::src_cpu is an SMT core with busy siblings, let
+	 * the lower priority @env::dst_cpu help it. Do not follow
+	 * CPU priority.
+	 */
+	return env->idle && sched_use_asym_prio(env->sd, env->dst_cpu) &&
+	       (sched_asym_prefer(env->dst_cpu, env->src_cpu) ||
+		!sched_use_asym_prio(env->sd, env->src_cpu));
+}
+
+static inline bool
+imbalanced_active_balance(struct lb_env *env)
+{
+	struct sched_domain *sd = env->sd;
+
+	/*
+	 * The imbalanced case includes the case of pinned tasks preventing a fair
+	 * distribution of the load on the system but also the even distribution of the
+	 * threads on a system with spare capacity
+	 */
+	if ((env->migration_type == migrate_task) &&
+	    (sd->nr_balance_failed > sd->cache_nice_tries+2))
+		return 1;
+
+	return 0;
+}
+
+static int need_active_balance(struct lb_env *env)
+{
+	struct sched_domain *sd = env->sd;
+
+	if (asym_active_balance(env))
+		return 1;
+
+	if (imbalanced_active_balance(env))
+		return 1;
+
+	/*
+	 * The dst_cpu is idle and the src_cpu CPU has only 1 CFS task.
+	 * It's worth migrating the task if the src_cpu's capacity is reduced
+	 * because of other sched_class or IRQs if more capacity stays
+	 * available on dst_cpu.
+	 */
+	if (env->idle &&
+	    (env->src_rq->cfs.h_nr_running == 1)) {
+		if ((check_cpu_capacity(env->src_rq, sd)) &&
+		    (capacity_of(env->src_cpu)*sd->imbalance_pct < capacity_of(env->dst_cpu)*100))
+			return 1;
+	}
+
+	if (env->migration_type == migrate_misfit)
+		return 1;
+
+	return 0;
+}
+
+static int active_load_balance_cpu_stop(void *data);
+
+static int should_we_balance(struct lb_env *env)
+{
+	struct cpumask *swb_cpus = this_cpu_cpumask_var_ptr(should_we_balance_tmpmask);
+	struct sched_group *sg = env->sd->groups;
+	int cpu, idle_smt = -1;
+
+	/*
+	 * Ensure the balancing environment is consistent; can happen
+	 * when the softirq triggers 'during' hotplug.
+	 */
+	if (!cpumask_test_cpu(env->dst_cpu, env->cpus))
+		return 0;
+
+	/*
+	 * In the newly idle case, we will allow all the CPUs
+	 * to do the newly idle load balance.
+	 *
+	 * However, we bail out if we already have tasks or a wakeup pending,
+	 * to optimize wakeup latency.
+	 */
+	if (env->idle == CPU_NEWLY_IDLE) {
+		if (env->dst_rq->nr_running > 0 || env->dst_rq->ttwu_pending)
+			return 0;
+		return 1;
+	}
+
+	cpumask_copy(swb_cpus, group_balance_mask(sg));
+	/* Try to find first idle CPU */
+	for_each_cpu_and(cpu, swb_cpus, env->cpus) {
+		if (!idle_cpu(cpu))
+			continue;
+
+		/*
+		 * Don't balance to idle SMT in busy core right away when
+		 * balancing cores, but remember the first idle SMT CPU for
+		 * later consideration.  Find CPU on an idle core first.
+		 */
+		if (!(env->sd->flags & SD_SHARE_CPUCAPACITY) && !is_core_idle(cpu)) {
+			if (idle_smt == -1)
+				idle_smt = cpu;
+			/*
+			 * If the core is not idle, and first SMT sibling which is
+			 * idle has been found, then its not needed to check other
+			 * SMT siblings for idleness:
+			 */
+#ifdef CONFIG_SCHED_SMT
+			cpumask_andnot(swb_cpus, swb_cpus, cpu_smt_mask(cpu));
+#endif
+			continue;
+		}
+
+		/*
+		 * Are we the first idle core in a non-SMT domain or higher,
+		 * or the first idle CPU in a SMT domain?
+		 */
+		return cpu == env->dst_cpu;
+	}
+
+	/* Are we the first idle CPU with busy siblings? */
+	if (idle_smt != -1)
+		return idle_smt == env->dst_cpu;
+
+	/* Are we the first CPU of this group ? */
+	return group_balance_cpu(sg) == env->dst_cpu;
+}
+
+/*
+ * Check this_cpu to ensure it is balanced within domain. Attempt to move
+ * tasks if there is an imbalance.
+ */
+static int sched_balance_rq(int this_cpu, struct rq *this_rq,
+			struct sched_domain *sd, enum cpu_idle_type idle,
+			int *continue_balancing)
+{
+	int ld_moved, cur_ld_moved, active_balance = 0;
+	struct sched_domain *sd_parent = sd->parent;
+	struct sched_group *group;
+	struct rq *busiest;
+	struct rq_flags rf;
+	struct cpumask *cpus = this_cpu_cpumask_var_ptr(load_balance_mask);
+	struct lb_env env = {
+		.sd		= sd,
+		.dst_cpu	= this_cpu,
+		.dst_rq		= this_rq,
+		.dst_grpmask    = group_balance_mask(sd->groups),
+		.idle		= idle,
+		.loop_break	= SCHED_NR_MIGRATE_BREAK,
+		.cpus		= cpus,
+		.fbq_type	= all,
+		.tasks		= LIST_HEAD_INIT(env.tasks),
+	};
+
+	cpumask_and(cpus, sched_domain_span(sd), cpu_active_mask);
+
+	schedstat_inc(sd->lb_count[idle]);
+
+redo:
+	if (!should_we_balance(&env)) {
+		*continue_balancing = 0;
+		goto out_balanced;
+	}
+
+	group = sched_balance_find_src_group(&env);
+	if (!group) {
+		schedstat_inc(sd->lb_nobusyg[idle]);
+		goto out_balanced;
+	}
+
+	busiest = sched_balance_find_src_rq(&env, group);
+	if (!busiest) {
+		schedstat_inc(sd->lb_nobusyq[idle]);
+		goto out_balanced;
+	}
+
+	WARN_ON_ONCE(busiest == env.dst_rq);
+
+	schedstat_add(sd->lb_imbalance[idle], env.imbalance);
+
+	env.src_cpu = busiest->cpu;
+	env.src_rq = busiest;
+
+	ld_moved = 0;
+	/* Clear this flag as soon as we find a pullable task */
+	env.flags |= LBF_ALL_PINNED;
+	if (busiest->nr_running > 1) {
+		/*
+		 * Attempt to move tasks. If sched_balance_find_src_group has found
+		 * an imbalance but busiest->nr_running <= 1, the group is
+		 * still unbalanced. ld_moved simply stays zero, so it is
+		 * correctly treated as an imbalance.
+		 */
+		env.loop_max  = min(sysctl_sched_nr_migrate, busiest->nr_running);
+
+more_balance:
+		rq_lock_irqsave(busiest, &rf);
+		update_rq_clock(busiest);
+
+		/*
+		 * cur_ld_moved - load moved in current iteration
+		 * ld_moved     - cumulative load moved across iterations
+		 */
+		cur_ld_moved = detach_tasks(&env);
+
+		/*
+		 * We've detached some tasks from busiest_rq. Every
+		 * task is masked "TASK_ON_RQ_MIGRATING", so we can safely
+		 * unlock busiest->lock, and we are able to be sure
+		 * that nobody can manipulate the tasks in parallel.
+		 * See task_rq_lock() family for the details.
+		 */
+
+		rq_unlock(busiest, &rf);
+
+		if (cur_ld_moved) {
+			attach_tasks(&env);
+			ld_moved += cur_ld_moved;
+		}
+
+		local_irq_restore(rf.flags);
+
+		if (env.flags & LBF_NEED_BREAK) {
+			env.flags &= ~LBF_NEED_BREAK;
+			/* Stop if we tried all running tasks */
+			if (env.loop < busiest->nr_running)
+				goto more_balance;
+		}
+
+		/*
+		 * Revisit (affine) tasks on src_cpu that couldn't be moved to
+		 * us and move them to an alternate dst_cpu in our sched_group
+		 * where they can run. The upper limit on how many times we
+		 * iterate on same src_cpu is dependent on number of CPUs in our
+		 * sched_group.
+		 *
+		 * This changes load balance semantics a bit on who can move
+		 * load to a given_cpu. In addition to the given_cpu itself
+		 * (or a ilb_cpu acting on its behalf where given_cpu is
+		 * nohz-idle), we now have balance_cpu in a position to move
+		 * load to given_cpu. In rare situations, this may cause
+		 * conflicts (balance_cpu and given_cpu/ilb_cpu deciding
+		 * _independently_ and at _same_ time to move some load to
+		 * given_cpu) causing excess load to be moved to given_cpu.
+		 * This however should not happen so much in practice and
+		 * moreover subsequent load balance cycles should correct the
+		 * excess load moved.
+		 */
+		if ((env.flags & LBF_DST_PINNED) && env.imbalance > 0) {
+
+			/* Prevent to re-select dst_cpu via env's CPUs */
+			__cpumask_clear_cpu(env.dst_cpu, env.cpus);
+
+			env.dst_rq	 = cpu_rq(env.new_dst_cpu);
+			env.dst_cpu	 = env.new_dst_cpu;
+			env.flags	&= ~LBF_DST_PINNED;
+			env.loop	 = 0;
+			env.loop_break	 = SCHED_NR_MIGRATE_BREAK;
+
+			/*
+			 * Go back to "more_balance" rather than "redo" since we
+			 * need to continue with same src_cpu.
+			 */
+			goto more_balance;
+		}
+
+		/*
+		 * We failed to reach balance because of affinity.
+		 */
+		if (sd_parent) {
+			int *group_imbalance = &sd_parent->groups->sgc->imbalance;
+
+			if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0)
+				*group_imbalance = 1;
+		}
+
+		/* All tasks on this runqueue were pinned by CPU affinity */
+		if (unlikely(env.flags & LBF_ALL_PINNED)) {
+			__cpumask_clear_cpu(cpu_of(busiest), cpus);
+			/*
+			 * Attempting to continue load balancing at the current
+			 * sched_domain level only makes sense if there are
+			 * active CPUs remaining as possible busiest CPUs to
+			 * pull load from which are not contained within the
+			 * destination group that is receiving any migrated
+			 * load.
+			 */
+			if (!cpumask_subset(cpus, env.dst_grpmask)) {
+				env.loop = 0;
+				env.loop_break = SCHED_NR_MIGRATE_BREAK;
+				goto redo;
+			}
+			goto out_all_pinned;
+		}
+	}
+
+	if (!ld_moved) {
+		schedstat_inc(sd->lb_failed[idle]);
+		/*
+		 * Increment the failure counter only on periodic balance.
+		 * We do not want newidle balance, which can be very
+		 * frequent, pollute the failure counter causing
+		 * excessive cache_hot migrations and active balances.
+		 *
+		 * Similarly for migration_misfit which is not related to
+		 * load/util migration, don't pollute nr_balance_failed.
+		 */
+		if (idle != CPU_NEWLY_IDLE &&
+		    env.migration_type != migrate_misfit)
+			sd->nr_balance_failed++;
+
+		if (need_active_balance(&env)) {
+			unsigned long flags;
+
+			raw_spin_rq_lock_irqsave(busiest, flags);
+
+			/*
+			 * Don't kick the active_load_balance_cpu_stop,
+			 * if the curr task on busiest CPU can't be
+			 * moved to this_cpu:
+			 */
+			if (!cpumask_test_cpu(this_cpu, busiest->curr->cpus_ptr)) {
+				raw_spin_rq_unlock_irqrestore(busiest, flags);
+				goto out_one_pinned;
+			}
+
+			/* Record that we found at least one task that could run on this_cpu */
+			env.flags &= ~LBF_ALL_PINNED;
+
+			/*
+			 * ->active_balance synchronizes accesses to
+			 * ->active_balance_work.  Once set, it's cleared
+			 * only after active load balance is finished.
+			 */
+			if (!busiest->active_balance) {
+				busiest->active_balance = 1;
+				busiest->push_cpu = this_cpu;
+				active_balance = 1;
+			}
+
+			preempt_disable();
+			raw_spin_rq_unlock_irqrestore(busiest, flags);
+			if (active_balance) {
+				stop_one_cpu_nowait(cpu_of(busiest),
+					active_load_balance_cpu_stop, busiest,
+					&busiest->active_balance_work);
+			}
+			preempt_enable();
+		}
+	} else {
+		sd->nr_balance_failed = 0;
+	}
+
+	if (likely(!active_balance) || need_active_balance(&env)) {
+		/* We were unbalanced, so reset the balancing interval */
+		sd->balance_interval = sd->min_interval;
+	}
+
+	goto out;
+
+out_balanced:
+	/*
+	 * We reach balance although we may have faced some affinity
+	 * constraints. Clear the imbalance flag only if other tasks got
+	 * a chance to move and fix the imbalance.
+	 */
+	if (sd_parent && !(env.flags & LBF_ALL_PINNED)) {
+		int *group_imbalance = &sd_parent->groups->sgc->imbalance;
+
+		if (*group_imbalance)
+			*group_imbalance = 0;
+	}
+
+out_all_pinned:
+	/*
+	 * We reach balance because all tasks are pinned at this level so
+	 * we can't migrate them. Let the imbalance flag set so parent level
+	 * can try to migrate them.
+	 */
+	schedstat_inc(sd->lb_balanced[idle]);
+
+	sd->nr_balance_failed = 0;
+
+out_one_pinned:
+	ld_moved = 0;
+
+	/*
+	 * sched_balance_newidle() disregards balance intervals, so we could
+	 * repeatedly reach this code, which would lead to balance_interval
+	 * skyrocketing in a short amount of time. Skip the balance_interval
+	 * increase logic to avoid that.
+	 *
+	 * Similarly misfit migration which is not necessarily an indication of
+	 * the system being busy and requires lb to backoff to let it settle
+	 * down.
+	 */
+	if (env.idle == CPU_NEWLY_IDLE ||
+	    env.migration_type == migrate_misfit)
+		goto out;
+
+	/* tune up the balancing interval */
+	if ((env.flags & LBF_ALL_PINNED &&
+	     sd->balance_interval < MAX_PINNED_INTERVAL) ||
+	    sd->balance_interval < sd->max_interval)
+		sd->balance_interval *= 2;
+out:
+	return ld_moved;
+}
+
+static inline unsigned long
+get_sd_balance_interval(struct sched_domain *sd, int cpu_busy)
+{
+	unsigned long interval = sd->balance_interval;
+
+	if (cpu_busy)
+		interval *= sd->busy_factor;
+
+	/* scale ms to jiffies */
+	interval = msecs_to_jiffies(interval);
+
+	/*
+	 * Reduce likelihood of busy balancing at higher domains racing with
+	 * balancing at lower domains by preventing their balancing periods
+	 * from being multiples of each other.
+	 */
+	if (cpu_busy)
+		interval -= 1;
+
+	interval = clamp(interval, 1UL, max_load_balance_interval);
+
+	return interval;
+}
+
+static inline void
+update_next_balance(struct sched_domain *sd, unsigned long *next_balance)
+{
+	unsigned long interval, next;
+
+	/* used by idle balance, so cpu_busy = 0 */
+	interval = get_sd_balance_interval(sd, 0);
+	next = sd->last_balance + interval;
+
+	if (time_after(*next_balance, next))
+		*next_balance = next;
+}
+
+/*
+ * active_load_balance_cpu_stop is run by the CPU stopper. It pushes
+ * running tasks off the busiest CPU onto idle CPUs. It requires at
+ * least 1 task to be running on each physical CPU where possible, and
+ * avoids physical / logical imbalances.
+ */
+static int active_load_balance_cpu_stop(void *data)
+{
+	struct rq *busiest_rq = data;
+	int busiest_cpu = cpu_of(busiest_rq);
+	int target_cpu = busiest_rq->push_cpu;
+	struct rq *target_rq = cpu_rq(target_cpu);
+	struct sched_domain *sd;
+	struct task_struct *p = NULL;
+	struct rq_flags rf;
+
+	rq_lock_irq(busiest_rq, &rf);
+	/*
+	 * Between queueing the stop-work and running it is a hole in which
+	 * CPUs can become inactive. We should not move tasks from or to
+	 * inactive CPUs.
+	 */
+	if (!cpu_active(busiest_cpu) || !cpu_active(target_cpu))
+		goto out_unlock;
+
+	/* Make sure the requested CPU hasn't gone down in the meantime: */
+	if (unlikely(busiest_cpu != smp_processor_id() ||
+		     !busiest_rq->active_balance))
+		goto out_unlock;
+
+	/* Is there any task to move? */
+	if (busiest_rq->nr_running <= 1)
+		goto out_unlock;
+
+	/*
+	 * This condition is "impossible", if it occurs
+	 * we need to fix it. Originally reported by
+	 * Bjorn Helgaas on a 128-CPU setup.
+	 */
+	WARN_ON_ONCE(busiest_rq == target_rq);
+
+	/* Search for an sd spanning us and the target CPU. */
+	rcu_read_lock();
+	for_each_domain(target_cpu, sd) {
+		if (cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
+			break;
+	}
+
+	if (likely(sd)) {
+		struct lb_env env = {
+			.sd		= sd,
+			.dst_cpu	= target_cpu,
+			.dst_rq		= target_rq,
+			.src_cpu	= busiest_rq->cpu,
+			.src_rq		= busiest_rq,
+			.idle		= CPU_IDLE,
+			.flags		= LBF_ACTIVE_LB,
+		};
+
+		schedstat_inc(sd->alb_count);
+		update_rq_clock(busiest_rq);
+
+		p = detach_one_task(&env);
+		if (p) {
+			schedstat_inc(sd->alb_pushed);
+			/* Active balancing done, reset the failure counter. */
+			sd->nr_balance_failed = 0;
+		} else {
+			schedstat_inc(sd->alb_failed);
+		}
+	}
+	rcu_read_unlock();
+out_unlock:
+	busiest_rq->active_balance = 0;
+	rq_unlock(busiest_rq, &rf);
+
+	if (p)
+		attach_one_task(target_rq, p);
+
+	local_irq_enable();
+
+	return 0;
+}
+
+/*
+ * This flag serializes load-balancing passes over large domains
+ * (above the NODE topology level) - only one load-balancing instance
+ * may run at a time, to reduce overhead on very large systems with
+ * lots of CPUs and large NUMA distances.
+ *
+ * - Note that load-balancing passes triggered while another one
+ *   is executing are skipped and not re-tried.
+ *
+ * - Also note that this does not serialize rebalance_domains()
+ *   execution, as non-SD_SERIALIZE domains will still be
+ *   load-balanced in parallel.
+ */
+static atomic_t sched_balance_running = ATOMIC_INIT(0);
+
+/*
+ * Scale the max sched_balance_rq interval with the number of CPUs in the system.
+ * This trades load-balance latency on larger machines for less cross talk.
+ */
+void update_max_interval(void)
+{
+	max_load_balance_interval = HZ*num_online_cpus()/10;
+}
+
+static inline bool update_newidle_cost(struct sched_domain *sd, u64 cost)
+{
+	if (cost > sd->max_newidle_lb_cost) {
+		/*
+		 * Track max cost of a domain to make sure to not delay the
+		 * next wakeup on the CPU.
+		 */
+		sd->max_newidle_lb_cost = cost;
+		sd->last_decay_max_lb_cost = jiffies;
+	} else if (time_after(jiffies, sd->last_decay_max_lb_cost + HZ)) {
+		/*
+		 * Decay the newidle max times by ~1% per second to ensure that
+		 * it is not outdated and the current max cost is actually
+		 * shorter.
+		 */
+		sd->max_newidle_lb_cost = (sd->max_newidle_lb_cost * 253) / 256;
+		sd->last_decay_max_lb_cost = jiffies;
+
+		return true;
+	}
+
+	return false;
+}
+
+/*
+ * It checks each scheduling domain to see if it is due to be balanced,
+ * and initiates a balancing operation if so.
+ *
+ * Balancing parameters are set up in init_sched_domains.
+ */
+static void sched_balance_domains(struct rq *rq, enum cpu_idle_type idle)
+{
+	int continue_balancing = 1;
+	int cpu = rq->cpu;
+	int busy = idle != CPU_IDLE && !sched_idle_cpu(cpu);
+	unsigned long interval;
+	struct sched_domain *sd;
+	/* Earliest time when we have to do rebalance again */
+	unsigned long next_balance = jiffies + 60*HZ;
+	int update_next_balance = 0;
+	int need_serialize, need_decay = 0;
+	u64 max_cost = 0;
+
+	rcu_read_lock();
+	for_each_domain(cpu, sd) {
+		/*
+		 * Decay the newidle max times here because this is a regular
+		 * visit to all the domains.
+		 */
+		need_decay = update_newidle_cost(sd, 0);
+		max_cost += sd->max_newidle_lb_cost;
+
+		/*
+		 * Stop the load balance at this level. There is another
+		 * CPU in our sched group which is doing load balancing more
+		 * actively.
+		 */
+		if (!continue_balancing) {
+			if (need_decay)
+				continue;
+			break;
+		}
+
+		interval = get_sd_balance_interval(sd, busy);
+
+		need_serialize = sd->flags & SD_SERIALIZE;
+		if (need_serialize) {
+			if (atomic_cmpxchg_acquire(&sched_balance_running, 0, 1))
+				goto out;
+		}
+
+		if (time_after_eq(jiffies, sd->last_balance + interval)) {
+			if (sched_balance_rq(cpu, rq, sd, idle, &continue_balancing)) {
+				/*
+				 * The LBF_DST_PINNED logic could have changed
+				 * env->dst_cpu, so we can't know our idle
+				 * state even if we migrated tasks. Update it.
+				 */
+				idle = idle_cpu(cpu);
+				busy = !idle && !sched_idle_cpu(cpu);
+			}
+			sd->last_balance = jiffies;
+			interval = get_sd_balance_interval(sd, busy);
+		}
+		if (need_serialize)
+			atomic_set_release(&sched_balance_running, 0);
+out:
+		if (time_after(next_balance, sd->last_balance + interval)) {
+			next_balance = sd->last_balance + interval;
+			update_next_balance = 1;
+		}
+	}
+	if (need_decay) {
+		/*
+		 * Ensure the rq-wide value also decays but keep it at a
+		 * reasonable floor to avoid funnies with rq->avg_idle.
+		 */
+		rq->max_idle_balance_cost =
+			max((u64)sysctl_sched_migration_cost, max_cost);
+	}
+	rcu_read_unlock();
+
+	/*
+	 * next_balance will be updated only when there is a need.
+	 * When the cpu is attached to null domain for ex, it will not be
+	 * updated.
+	 */
+	if (likely(update_next_balance))
+		rq->next_balance = next_balance;
+
+}
+
+static inline int on_null_domain(struct rq *rq)
+{
+	return unlikely(!rcu_dereference_sched(rq->sd));
+}
+
+#ifdef CONFIG_NO_HZ_COMMON
+/*
+ * NOHZ idle load balancing (ILB) details:
+ *
+ * - When one of the busy CPUs notices that there may be an idle rebalancing
+ *   needed, they will kick the idle load balancer, which then does idle
+ *   load balancing for all the idle CPUs.
+ *
+ * - HK_TYPE_MISC CPUs are used for this task, because HK_TYPE_SCHED is not set
+ *   anywhere yet.
+ */
+static inline int find_new_ilb(void)
+{
+	const struct cpumask *hk_mask;
+	int ilb_cpu;
+
+	hk_mask = housekeeping_cpumask(HK_TYPE_MISC);
+
+	for_each_cpu_and(ilb_cpu, nohz.idle_cpus_mask, hk_mask) {
+
+		if (ilb_cpu == smp_processor_id())
+			continue;
+
+		if (idle_cpu(ilb_cpu))
+			return ilb_cpu;
+	}
+
+	return -1;
+}
+
+/*
+ * Kick a CPU to do the NOHZ balancing, if it is time for it, via a cross-CPU
+ * SMP function call (IPI).
+ *
+ * We pick the first idle CPU in the HK_TYPE_MISC housekeeping set (if there is one).
+ */
+static void kick_ilb(unsigned int flags)
+{
+	int ilb_cpu;
+
+	/*
+	 * Increase nohz.next_balance only when if full ilb is triggered but
+	 * not if we only update stats.
+	 */
+	if (flags & NOHZ_BALANCE_KICK)
+		nohz.next_balance = jiffies+1;
+
+	ilb_cpu = find_new_ilb();
+	if (ilb_cpu < 0)
+		return;
+
+	/*
+	 * Access to rq::nohz_csd is serialized by NOHZ_KICK_MASK; he who sets
+	 * the first flag owns it; cleared by nohz_csd_func().
+	 */
+	flags = atomic_fetch_or(flags, nohz_flags(ilb_cpu));
+	if (flags & NOHZ_KICK_MASK)
+		return;
+
+	/*
+	 * This way we generate an IPI on the target CPU which
+	 * is idle, and the softirq performing NOHZ idle load balancing
+	 * will be run before returning from the IPI.
+	 */
+	smp_call_function_single_async(ilb_cpu, &cpu_rq(ilb_cpu)->nohz_csd);
+}
+
+/*
+ * Current decision point for kicking the idle load balancer in the presence
+ * of idle CPUs in the system.
+ */
+static void nohz_balancer_kick(struct rq *rq)
+{
+	unsigned long now = jiffies;
+	struct sched_domain_shared *sds;
+	struct sched_domain *sd;
+	int nr_busy, i, cpu = rq->cpu;
+	unsigned int flags = 0;
+
+	if (unlikely(rq->idle_balance))
+		return;
+
+	/*
+	 * We may be recently in ticked or tickless idle mode. At the first
+	 * busy tick after returning from idle, we will update the busy stats.
+	 */
+	nohz_balance_exit_idle(rq);
+
+	/*
+	 * None are in tickless mode and hence no need for NOHZ idle load
+	 * balancing:
+	 */
+	if (likely(!atomic_read(&nohz.nr_cpus)))
+		return;
+
+	if (READ_ONCE(nohz.has_blocked) &&
+	    time_after(now, READ_ONCE(nohz.next_blocked)))
+		flags = NOHZ_STATS_KICK;
+
+	if (time_before(now, nohz.next_balance))
+		goto out;
+
+	if (rq->nr_running >= 2) {
+		flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
+		goto out;
+	}
+
+	rcu_read_lock();
+
+	sd = rcu_dereference(rq->sd);
+	if (sd) {
+		/*
+		 * If there's a runnable CFS task and the current CPU has reduced
+		 * capacity, kick the ILB to see if there's a better CPU to run on:
+		 */
+		if (rq->cfs.h_nr_running >= 1 && check_cpu_capacity(rq, sd)) {
+			flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
+			goto unlock;
+		}
+	}
+
+	sd = rcu_dereference(per_cpu(sd_asym_packing, cpu));
+	if (sd) {
+		/*
+		 * When ASYM_PACKING; see if there's a more preferred CPU
+		 * currently idle; in which case, kick the ILB to move tasks
+		 * around.
+		 *
+		 * When balancing between cores, all the SMT siblings of the
+		 * preferred CPU must be idle.
+		 */
+		for_each_cpu_and(i, sched_domain_span(sd), nohz.idle_cpus_mask) {
+			if (sched_asym(sd, i, cpu)) {
+				flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
+				goto unlock;
+			}
+		}
+	}
+
+	sd = rcu_dereference(per_cpu(sd_asym_cpucapacity, cpu));
+	if (sd) {
+		/*
+		 * When ASYM_CPUCAPACITY; see if there's a higher capacity CPU
+		 * to run the misfit task on.
+		 */
+		if (check_misfit_status(rq)) {
+			flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
+			goto unlock;
+		}
+
+		/*
+		 * For asymmetric systems, we do not want to nicely balance
+		 * cache use, instead we want to embrace asymmetry and only
+		 * ensure tasks have enough CPU capacity.
+		 *
+		 * Skip the LLC logic because it's not relevant in that case.
+		 */
+		goto unlock;
+	}
+
+	sds = rcu_dereference(per_cpu(sd_llc_shared, cpu));
+	if (sds) {
+		/*
+		 * If there is an imbalance between LLC domains (IOW we could
+		 * increase the overall cache utilization), we need a less-loaded LLC
+		 * domain to pull some load from. Likewise, we may need to spread
+		 * load within the current LLC domain (e.g. packed SMT cores but
+		 * other CPUs are idle). We can't really know from here how busy
+		 * the others are - so just get a NOHZ balance going if it looks
+		 * like this LLC domain has tasks we could move.
+		 */
+		nr_busy = atomic_read(&sds->nr_busy_cpus);
+		if (nr_busy > 1) {
+			flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK;
+			goto unlock;
+		}
+	}
+unlock:
+	rcu_read_unlock();
+out:
+	if (READ_ONCE(nohz.needs_update))
+		flags |= NOHZ_NEXT_KICK;
+
+	if (flags)
+		kick_ilb(flags);
+}
+
+static void set_cpu_sd_state_busy(int cpu)
+{
+	struct sched_domain *sd;
+
+	rcu_read_lock();
+	sd = rcu_dereference(per_cpu(sd_llc, cpu));
+
+	if (!sd || !sd->nohz_idle)
+		goto unlock;
+	sd->nohz_idle = 0;
+
+	atomic_inc(&sd->shared->nr_busy_cpus);
+unlock:
+	rcu_read_unlock();
+}
+
+void nohz_balance_exit_idle(struct rq *rq)
+{
+	SCHED_WARN_ON(rq != this_rq());
+
+	if (likely(!rq->nohz_tick_stopped))
+		return;
+
+	rq->nohz_tick_stopped = 0;
+	cpumask_clear_cpu(rq->cpu, nohz.idle_cpus_mask);
+	atomic_dec(&nohz.nr_cpus);
+
+	set_cpu_sd_state_busy(rq->cpu);
+}
+
+static void set_cpu_sd_state_idle(int cpu)
+{
+	struct sched_domain *sd;
+
+	rcu_read_lock();
+	sd = rcu_dereference(per_cpu(sd_llc, cpu));
+
+	if (!sd || sd->nohz_idle)
+		goto unlock;
+	sd->nohz_idle = 1;
+
+	atomic_dec(&sd->shared->nr_busy_cpus);
+unlock:
+	rcu_read_unlock();
+}
+
+/*
+ * This routine will record that the CPU is going idle with tick stopped.
+ * This info will be used in performing idle load balancing in the future.
+ */
+void nohz_balance_enter_idle(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+
+	SCHED_WARN_ON(cpu != smp_processor_id());
+
+	/* If this CPU is going down, then nothing needs to be done: */
+	if (!cpu_active(cpu))
+		return;
+
+	/* Spare idle load balancing on CPUs that don't want to be disturbed: */
+	if (!housekeeping_cpu(cpu, HK_TYPE_SCHED))
+		return;
+
+	/*
+	 * Can be set safely without rq->lock held
+	 * If a clear happens, it will have evaluated last additions because
+	 * rq->lock is held during the check and the clear
+	 */
+	rq->has_blocked_load = 1;
+
+	/*
+	 * The tick is still stopped but load could have been added in the
+	 * meantime. We set the nohz.has_blocked flag to trig a check of the
+	 * *_avg. The CPU is already part of nohz.idle_cpus_mask so the clear
+	 * of nohz.has_blocked can only happen after checking the new load
+	 */
+	if (rq->nohz_tick_stopped)
+		goto out;
+
+	/* If we're a completely isolated CPU, we don't play: */
+	if (on_null_domain(rq))
+		return;
+
+	rq->nohz_tick_stopped = 1;
+
+	cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
+	atomic_inc(&nohz.nr_cpus);
+
+	/*
+	 * Ensures that if nohz_idle_balance() fails to observe our
+	 * @idle_cpus_mask store, it must observe the @has_blocked
+	 * and @needs_update stores.
+	 */
+	smp_mb__after_atomic();
+
+	set_cpu_sd_state_idle(cpu);
+
+	WRITE_ONCE(nohz.needs_update, 1);
+out:
+	/*
+	 * Each time a cpu enter idle, we assume that it has blocked load and
+	 * enable the periodic update of the load of idle CPUs
+	 */
+	WRITE_ONCE(nohz.has_blocked, 1);
+}
+
+static bool update_nohz_stats(struct rq *rq)
+{
+	unsigned int cpu = rq->cpu;
+
+	if (!rq->has_blocked_load)
+		return false;
+
+	if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))
+		return false;
+
+	if (!time_after(jiffies, READ_ONCE(rq->last_blocked_load_update_tick)))
+		return true;
+
+	sched_balance_update_blocked_averages(cpu);
+
+	return rq->has_blocked_load;
+}
+
+/*
+ * Internal function that runs load balance for all idle CPUs. The load balance
+ * can be a simple update of blocked load or a complete load balance with
+ * tasks movement depending of flags.
+ */
+static void _nohz_idle_balance(struct rq *this_rq, unsigned int flags)
+{
+	/* Earliest time when we have to do rebalance again */
+	unsigned long now = jiffies;
+	unsigned long next_balance = now + 60*HZ;
+	bool has_blocked_load = false;
+	int update_next_balance = 0;
+	int this_cpu = this_rq->cpu;
+	int balance_cpu;
+	struct rq *rq;
+
+	SCHED_WARN_ON((flags & NOHZ_KICK_MASK) == NOHZ_BALANCE_KICK);
+
+	/*
+	 * We assume there will be no idle load after this update and clear
+	 * the has_blocked flag. If a cpu enters idle in the mean time, it will
+	 * set the has_blocked flag and trigger another update of idle load.
+	 * Because a cpu that becomes idle, is added to idle_cpus_mask before
+	 * setting the flag, we are sure to not clear the state and not
+	 * check the load of an idle cpu.
+	 *
+	 * Same applies to idle_cpus_mask vs needs_update.
+	 */
+	if (flags & NOHZ_STATS_KICK)
+		WRITE_ONCE(nohz.has_blocked, 0);
+	if (flags & NOHZ_NEXT_KICK)
+		WRITE_ONCE(nohz.needs_update, 0);
+
+	/*
+	 * Ensures that if we miss the CPU, we must see the has_blocked
+	 * store from nohz_balance_enter_idle().
+	 */
+	smp_mb();
+
+	/*
+	 * Start with the next CPU after this_cpu so we will end with this_cpu and let a
+	 * chance for other idle cpu to pull load.
+	 */
+	for_each_cpu_wrap(balance_cpu,  nohz.idle_cpus_mask, this_cpu+1) {
+		if (!idle_cpu(balance_cpu))
+			continue;
+
+		/*
+		 * If this CPU gets work to do, stop the load balancing
+		 * work being done for other CPUs. Next load
+		 * balancing owner will pick it up.
+		 */
+		if (need_resched()) {
+			if (flags & NOHZ_STATS_KICK)
+				has_blocked_load = true;
+			if (flags & NOHZ_NEXT_KICK)
+				WRITE_ONCE(nohz.needs_update, 1);
+			goto abort;
+		}
+
+		rq = cpu_rq(balance_cpu);
+
+		if (flags & NOHZ_STATS_KICK)
+			has_blocked_load |= update_nohz_stats(rq);
+
+		/*
+		 * If time for next balance is due,
+		 * do the balance.
+		 */
+		if (time_after_eq(jiffies, rq->next_balance)) {
+			struct rq_flags rf;
+
+			rq_lock_irqsave(rq, &rf);
+			update_rq_clock(rq);
+			rq_unlock_irqrestore(rq, &rf);
+
+			if (flags & NOHZ_BALANCE_KICK)
+				sched_balance_domains(rq, CPU_IDLE);
+		}
+
+		if (time_after(next_balance, rq->next_balance)) {
+			next_balance = rq->next_balance;
+			update_next_balance = 1;
+		}
+	}
+
+	/*
+	 * next_balance will be updated only when there is a need.
+	 * When the CPU is attached to null domain for ex, it will not be
+	 * updated.
+	 */
+	if (likely(update_next_balance))
+		nohz.next_balance = next_balance;
+
+	if (flags & NOHZ_STATS_KICK)
+		WRITE_ONCE(nohz.next_blocked,
+			   now + msecs_to_jiffies(LOAD_AVG_PERIOD));
+
+abort:
+	/* There is still blocked load, enable periodic update */
+	if (has_blocked_load)
+		WRITE_ONCE(nohz.has_blocked, 1);
+}
+
+/*
+ * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the
+ * rebalancing for all the CPUs for whom scheduler ticks are stopped.
+ */
+static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
+{
+	unsigned int flags = this_rq->nohz_idle_balance;
+
+	if (!flags)
+		return false;
+
+	this_rq->nohz_idle_balance = 0;
+
+	if (idle != CPU_IDLE)
+		return false;
+
+	_nohz_idle_balance(this_rq, flags);
+
+	return true;
+}
+
+/*
+ * Check if we need to directly run the ILB for updating blocked load before
+ * entering idle state. Here we run ILB directly without issuing IPIs.
+ *
+ * Note that when this function is called, the tick may not yet be stopped on
+ * this CPU yet. nohz.idle_cpus_mask is updated only when tick is stopped and
+ * cleared on the next busy tick. In other words, nohz.idle_cpus_mask updates
+ * don't align with CPUs enter/exit idle to avoid bottlenecks due to high idle
+ * entry/exit rate (usec). So it is possible that _nohz_idle_balance() is
+ * called from this function on (this) CPU that's not yet in the mask. That's
+ * OK because the goal of nohz_run_idle_balance() is to run ILB only for
+ * updating the blocked load of already idle CPUs without waking up one of
+ * those idle CPUs and outside the preempt disable / IRQ off phase of the local
+ * cpu about to enter idle, because it can take a long time.
+ */
+void nohz_run_idle_balance(int cpu)
+{
+	unsigned int flags;
+
+	flags = atomic_fetch_andnot(NOHZ_NEWILB_KICK, nohz_flags(cpu));
+
+	/*
+	 * Update the blocked load only if no SCHED_SOFTIRQ is about to happen
+	 * (i.e. NOHZ_STATS_KICK set) and will do the same.
+	 */
+	if ((flags == NOHZ_NEWILB_KICK) && !need_resched())
+		_nohz_idle_balance(cpu_rq(cpu), NOHZ_STATS_KICK);
+}
+
+static void nohz_newidle_balance(struct rq *this_rq)
+{
+	int this_cpu = this_rq->cpu;
+
+	/*
+	 * This CPU doesn't want to be disturbed by scheduler
+	 * housekeeping
+	 */
+	if (!housekeeping_cpu(this_cpu, HK_TYPE_SCHED))
+		return;
+
+	/* Will wake up very soon. No time for doing anything else*/
+	if (this_rq->avg_idle < sysctl_sched_migration_cost)
+		return;
+
+	/* Don't need to update blocked load of idle CPUs*/
+	if (!READ_ONCE(nohz.has_blocked) ||
+	    time_before(jiffies, READ_ONCE(nohz.next_blocked)))
+		return;
+
+	/*
+	 * Set the need to trigger ILB in order to update blocked load
+	 * before entering idle state.
+	 */
+	atomic_or(NOHZ_NEWILB_KICK, nohz_flags(this_cpu));
+}
+
+#else /* !CONFIG_NO_HZ_COMMON */
+static inline void nohz_balancer_kick(struct rq *rq) { }
+
+static inline bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
+{
+	return false;
+}
+
+static inline void nohz_newidle_balance(struct rq *this_rq) { }
+#endif /* CONFIG_NO_HZ_COMMON */
+
+/*
+ * sched_balance_newidle is called by schedule() if this_cpu is about to become
+ * idle. Attempts to pull tasks from other CPUs.
+ *
+ * Returns:
+ *   < 0 - we released the lock and there are !fair tasks present
+ *     0 - failed, no new tasks
+ *   > 0 - success, new (fair) tasks present
+ */
+int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf)
+{
+	unsigned long next_balance = jiffies + HZ;
+	int this_cpu = this_rq->cpu;
+	int continue_balancing = 1;
+	u64 t0, t1, curr_cost = 0;
+	struct sched_domain *sd;
+	int pulled_task = 0;
+
+	update_misfit_status(NULL, this_rq);
+
+	/*
+	 * There is a task waiting to run. No need to search for one.
+	 * Return 0; the task will be enqueued when switching to idle.
+	 */
+	if (this_rq->ttwu_pending)
+		return 0;
+
+	/*
+	 * We must set idle_stamp _before_ calling sched_balance_rq()
+	 * for CPU_NEWLY_IDLE, such that we measure the this duration
+	 * as idle time.
+	 */
+	this_rq->idle_stamp = rq_clock(this_rq);
+
+	/*
+	 * Do not pull tasks towards !active CPUs...
+	 */
+	if (!cpu_active(this_cpu))
+		return 0;
+
+	/*
+	 * This is OK, because current is on_cpu, which avoids it being picked
+	 * for load-balance and preemption/IRQs are still disabled avoiding
+	 * further scheduler activity on it and we're being very careful to
+	 * re-start the picking loop.
+	 */
+	rq_unpin_lock(this_rq, rf);
+
+	rcu_read_lock();
+	sd = rcu_dereference_check_sched_domain(this_rq->sd);
+
+	if (!get_rd_overloaded(this_rq->rd) ||
+	    (sd && this_rq->avg_idle < sd->max_newidle_lb_cost)) {
+
+		if (sd)
+			update_next_balance(sd, &next_balance);
+		rcu_read_unlock();
+
+		goto out;
+	}
+	rcu_read_unlock();
+
+	raw_spin_rq_unlock(this_rq);
+
+	t0 = sched_clock_cpu(this_cpu);
+	sched_balance_update_blocked_averages(this_cpu);
+
+	rcu_read_lock();
+	for_each_domain(this_cpu, sd) {
+		u64 domain_cost;
+
+		update_next_balance(sd, &next_balance);
+
+		if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost)
+			break;
+
+		if (sd->flags & SD_BALANCE_NEWIDLE) {
+
+			pulled_task = sched_balance_rq(this_cpu, this_rq,
+						   sd, CPU_NEWLY_IDLE,
+						   &continue_balancing);
+
+			t1 = sched_clock_cpu(this_cpu);
+			domain_cost = t1 - t0;
+			update_newidle_cost(sd, domain_cost);
+
+			curr_cost += domain_cost;
+			t0 = t1;
+		}
+
+		/*
+		 * Stop searching for tasks to pull if there are
+		 * now runnable tasks on this rq.
+		 */
+		if (pulled_task || !continue_balancing)
+			break;
+	}
+	rcu_read_unlock();
+
+	raw_spin_rq_lock(this_rq);
+
+	if (curr_cost > this_rq->max_idle_balance_cost)
+		this_rq->max_idle_balance_cost = curr_cost;
+
+	/*
+	 * While browsing the domains, we released the rq lock, a task could
+	 * have been enqueued in the meantime. Since we're not going idle,
+	 * pretend we pulled a task.
+	 */
+	if (this_rq->cfs.h_nr_running && !pulled_task)
+		pulled_task = 1;
+
+	/* Is there a task of a high priority class? */
+	if (this_rq->nr_running != this_rq->cfs.h_nr_running)
+		pulled_task = -1;
+
+out:
+	/* Move the next balance forward */
+	if (time_after(this_rq->next_balance, next_balance))
+		this_rq->next_balance = next_balance;
+
+	if (pulled_task)
+		this_rq->idle_stamp = 0;
+	else
+		nohz_newidle_balance(this_rq);
+
+	rq_repin_lock(this_rq, rf);
+
+	return pulled_task;
+}
+
+/*
+ * This softirq handler is triggered via SCHED_SOFTIRQ from two places:
+ *
+ * - directly from the local scheduler_tick() for periodic load balancing
+ *
+ * - indirectly from a remote scheduler_tick() for NOHZ idle balancing
+ *   through the SMP cross-call nohz_csd_func()
+ */
+__latent_entropy void sched_balance_softirq(struct softirq_action *h)
+{
+	struct rq *this_rq = this_rq();
+	enum cpu_idle_type idle = this_rq->idle_balance;
+	/*
+	 * If this CPU has a pending NOHZ_BALANCE_KICK, then do the
+	 * balancing on behalf of the other idle CPUs whose ticks are
+	 * stopped. Do nohz_idle_balance *before* sched_balance_domains to
+	 * give the idle CPUs a chance to load balance. Else we may
+	 * load balance only within the local sched_domain hierarchy
+	 * and abort nohz_idle_balance altogether if we pull some load.
+	 */
+	if (nohz_idle_balance(this_rq, idle))
+		return;
+
+	/* normal load balance */
+	sched_balance_update_blocked_averages(this_rq->cpu);
+	sched_balance_domains(this_rq, idle);
+}
+
+/*
+ * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
+ */
+void sched_balance_trigger(struct rq *rq)
+{
+	/*
+	 * Don't need to rebalance while attached to NULL domain or
+	 * runqueue CPU is not active
+	 */
+	if (unlikely(on_null_domain(rq) || !cpu_active(cpu_of(rq))))
+		return;
+
+	if (time_after_eq(jiffies, rq->next_balance))
+		raise_softirq(SCHED_SOFTIRQ);
+
+	nohz_balancer_kick(rq);
+}
+
+#endif /* CONFIG_SMP */
+
+__init void init_sched_fair_class_balance(void)
+{
+#ifdef CONFIG_SMP
+	int i;
+
+	for_each_possible_cpu(i) {
+		zalloc_cpumask_var_node(&per_cpu(load_balance_mask, i), GFP_KERNEL, cpu_to_node(i));
+		zalloc_cpumask_var_node(&per_cpu(should_we_balance_tmpmask, i),
+					GFP_KERNEL, cpu_to_node(i));
+
+	}
+
+	open_softirq(SCHED_SOFTIRQ, sched_balance_softirq);
+
+#ifdef CONFIG_NO_HZ_COMMON
+	nohz.next_balance = jiffies;
+	nohz.next_blocked = jiffies;
+	zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
+#endif
+#endif /* SMP */
+}
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 18b4c8147364..7f1d856fdc3b 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2502,6 +2502,7 @@ extern void update_max_interval(void);
 extern void init_sched_dl_class(void);
 extern void init_sched_rt_class(void);
 extern void init_sched_fair_class(void);
+extern void init_sched_fair_class_balance(void);
 
 extern void reweight_task(struct task_struct *p, int prio);
 
@@ -3088,6 +3089,11 @@ static inline unsigned long cpu_util_rt(struct rq *rq)
 {
 	return READ_ONCE(rq->avg_rt.util_avg);
 }
+
+extern unsigned long cpu_load_without(struct rq *rq, struct task_struct *p);
+extern unsigned long cpu_runnable_without(struct rq *rq, struct task_struct *p);
+extern unsigned long cpu_util_without(int cpu, struct task_struct *p);
+
 #endif
 
 #ifdef CONFIG_UCLAMP_TASK
@@ -3594,4 +3600,254 @@ static inline void balance_callbacks(struct rq *rq, struct balance_callback *hea
 
 #endif
 
+#ifdef CONFIG_SMP
+int sched_balance_newidle(struct rq *this_rq, struct rq_flags *rf);
+extern struct sched_group *
+sched_balance_find_dst_group(struct sched_domain *sd, struct task_struct *p, int this_cpu);
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+extern unsigned long task_h_load(struct task_struct *p);
+#else
+static unsigned long task_h_load(struct task_struct *p)
+{
+	return p->se.avg.load_avg;
+}
+#endif
+
+#else /* !CONFIG_SMP: */
+static inline int sched_balance_newidle(struct rq *rq, struct rq_flags *rf)
+{
+	return 0;
+}
+#endif /* !CONFIG_SMP */
+
+extern __latent_entropy void sched_balance_softirq(struct softirq_action *h);
+
+#ifdef CONFIG_CFS_BANDWIDTH
+extern int throttled_lb_pair(struct task_group *tg, int src_cpu, int dest_cpu);
+#else
+static inline int throttled_lb_pair(struct task_group *tg,
+				    int src_cpu, int dest_cpu)
+{
+	return 0;
+}
+#endif
+
+extern void cfs_rq_util_change(struct cfs_rq *cfs_rq, int flags);
+
+#ifdef CONFIG_SMP
+
+static inline unsigned long task_util(struct task_struct *p)
+{
+	return READ_ONCE(p->se.avg.util_avg);
+}
+
+static inline unsigned long _task_util_est(struct task_struct *p)
+{
+	return READ_ONCE(p->se.avg.util_est) & ~UTIL_AVG_UNCHANGED;
+}
+
+static inline unsigned long task_util_est(struct task_struct *p)
+{
+	return max(task_util(p), _task_util_est(p));
+}
+
+/*
+ * Optional action to be done while updating the load average
+ */
+#define UPDATE_TG	0x1
+#define SKIP_AGE_LOAD	0x2
+#define DO_ATTACH	0x4
+#define DO_DETACH	0x8
+
+extern void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags);
+
+static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq)
+{
+	return cfs_rq->avg.load_avg;
+}
+
+static inline unsigned long cpu_load(struct rq *rq)
+{
+	return cfs_rq_load_avg(&rq->cfs);
+}
+
+#else /* !CONFIG_SMP: */
+
+#define UPDATE_TG	0x0
+#define SKIP_AGE_LOAD	0x0
+#define DO_ATTACH	0x0
+#define DO_DETACH	0x0
+
+static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int not_used1)
+{
+	cfs_rq_util_change(cfs_rq, 0);
+}
+
+#endif /* !CONFIG_SMP */
+
+#ifdef CONFIG_SMP
+extern void enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se);
+extern void dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se);
+extern void check_update_overutilized_status(struct rq *rq);
+extern void util_est_enqueue(struct cfs_rq *cfs_rq, struct task_struct *p);
+extern void util_est_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p);
+extern void util_est_update(struct cfs_rq *cfs_rq, struct task_struct *p, bool task_sleep);
+#else
+static inline void enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
+static inline void dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
+static inline void check_update_overutilized_status(struct rq *rq) { }
+static inline void util_est_enqueue(struct cfs_rq *cfs_rq, struct task_struct *p) {}
+static inline void util_est_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p) {}
+static inline void util_est_update(struct cfs_rq *cfs_rq, struct task_struct *p, bool task_sleep) {}
+#endif
+
+#ifdef CONFIG_SMP
+/*
+ * Signed add and clamp on underflow.
+ *
+ * Explicitly do a load-store to ensure the intermediate value never hits
+ * memory. This allows lockless observations without ever seeing the negative
+ * values.
+ */
+#define add_positive(_ptr, _val) do {                           \
+	typeof(_ptr) ptr = (_ptr);                              \
+	typeof(_val) val = (_val);                              \
+	typeof(*ptr) res, var = READ_ONCE(*ptr);                \
+								\
+	res = var + val;                                        \
+								\
+	if (val < 0 && res > var)                               \
+		res = 0;                                        \
+								\
+	WRITE_ONCE(*ptr, res);                                  \
+} while (0)
+
+/*
+ * Unsigned subtract and clamp on underflow.
+ *
+ * Explicitly do a load-store to ensure the intermediate value never hits
+ * memory. This allows lockless observations without ever seeing the negative
+ * values.
+ */
+#define sub_positive(_ptr, _val) do {				\
+	typeof(_ptr) ptr = (_ptr);				\
+	typeof(*ptr) val = (_val);				\
+	typeof(*ptr) res, var = READ_ONCE(*ptr);		\
+	res = var - val;					\
+	if (res > var)						\
+		res = 0;					\
+	WRITE_ONCE(*ptr, res);					\
+} while (0)
+
+/*
+ * Remove and clamp on negative, from a local variable.
+ *
+ * A variant of sub_positive(), which does not use explicit load-store
+ * and is thus optimized for local variable updates.
+ */
+#define lsub_positive(_ptr, _val) do {				\
+	typeof(_ptr) ptr = (_ptr);				\
+	*ptr -= min_t(typeof(*ptr), *ptr, _val);		\
+} while (0)
+
+extern void sync_entity_load_avg(struct sched_entity *se);
+
+extern
+int util_fits_cpu(unsigned long util,
+		  unsigned long uclamp_min,
+		  unsigned long uclamp_max,
+		  int cpu);
+
+/*
+ * overutilized value make sense only if EAS is enabled
+ */
+static inline bool is_rd_overutilized(struct root_domain *rd)
+{
+	return !sched_energy_enabled() || READ_ONCE(rd->overutilized);
+}
+
+#ifdef CONFIG_NO_HZ_COMMON
+extern void migrate_se_pelt_lag(struct sched_entity *se);
+#else
+static inline void migrate_se_pelt_lag(struct sched_entity *se) {}
+#endif
+
+extern void clear_tg_offline_cfs_rqs(struct rq *rq);
+
+DECLARE_PER_CPU(cpumask_var_t, select_rq_mask);
+
+extern void update_tg_load_avg(struct cfs_rq *cfs_rq);
+
+static inline unsigned long capacity_of(int cpu)
+{
+	return cpu_rq(cpu)->cpu_capacity;
+}
+
+extern bool is_core_idle(int cpu);
+
+extern unsigned long cpu_runnable(struct rq *rq);
+
+extern int sched_idle_cpu(int cpu);
+
+#else /* !CONFIG_SMP: */
+
+static inline void update_tg_load_avg(struct cfs_rq *cfs_rq) { }
+
+#endif /* !CONFIG_SMP */
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+
+/* Iterate through all leaf cfs_rq's on a runqueue */
+#define for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos)			\
+	list_for_each_entry_safe(cfs_rq, pos, &rq->leaf_cfs_rq_list,	\
+				 leaf_cfs_rq_list)
+
+extern void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq);
+
+/* Walk up scheduling entities hierarchy */
+
+#define for_each_sched_entity(se) \
+		for (; se; se = se->parent)
+
+extern bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq);
+
+#else /* !CONFIG_FAIR_GROUP_SCHED: */
+
+#define for_each_leaf_cfs_rq_safe(rq, cfs_rq, pos)	\
+		for (cfs_rq = &rq->cfs, pos = NULL; cfs_rq; cfs_rq = pos)
+
+static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) { }
+
+#define for_each_sched_entity(se) \
+		for (; se; se = NULL)
+
+static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
+{
+	return !cfs_rq->nr_running;
+}
+
+#endif /* !CONFIG_FAIR_GROUP_SCHED */
+
+#ifdef CONFIG_NUMA
+extern long adjust_numa_imbalance(int imbalance, int dst_running, int imb_numa_nr);
+#endif
+
+#ifdef CONFIG_NUMA_BALANCING
+extern unsigned long task_weight(struct task_struct *p, int nid, int dist);
+extern unsigned long group_weight(struct task_struct *p, int nid, int dist);
+#endif
+
+#ifdef CONFIG_SMP
+extern void update_misfit_status(struct task_struct *p, struct rq *rq);
+extern void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se);
+extern void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se);
+extern void remove_entity_load_avg(struct sched_entity *se);
+#else
+static inline void update_misfit_status(struct task_struct *p, struct rq *rq) {}
+static inline void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
+static inline void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
+static inline void remove_entity_load_avg(struct sched_entity *se) {}
+#endif
+
 #endif /* _KERNEL_SCHED_SCHED_H */
-- 
2.40.1