[PATCH V6 6/6] sched/rt: Remove default bandwidth control
From: Daniel Bristot de Oliveira
Date: Fri Apr 05 2024 - 13:34:42 EST
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Now that fair_server exists, we no longer need RT bandwidth control
unless RT_GROUP_SCHED.
Enable fair_server with parameters equivalent to RT throttling.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
---
kernel/sched/core.c | 9 +-
kernel/sched/deadline.c | 5 +-
kernel/sched/debug.c | 3 +
kernel/sched/rt.c | 242 ++++++++++++++++++----------------------
kernel/sched/sched.h | 3 +-
5 files changed, 120 insertions(+), 142 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4881e797ae07..d70bfc7e3e7b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9988,8 +9988,6 @@ void __init sched_init(void)
#endif /* CONFIG_RT_GROUP_SCHED */
}
- init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime());
-
#ifdef CONFIG_SMP
init_defrootdomain();
#endif
@@ -10044,8 +10042,13 @@ void __init sched_init(void)
init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
#endif /* CONFIG_FAIR_GROUP_SCHED */
- rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
#ifdef CONFIG_RT_GROUP_SCHED
+ /*
+ * This is required for init cpu because rt.c:__enable_runtime()
+ * starts working after scheduler_running, which is not the case
+ * yet.
+ */
+ rq->rt.rt_runtime = global_rt_runtime();
init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
#endif
#ifdef CONFIG_SMP
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 45fde2fd3a1b..f0a7f0e43ff0 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1554,6 +1554,7 @@ static void update_curr_dl_se(struct rq *rq, struct sched_dl_entity *dl_se, s64
if (dl_se == &rq->fair_server)
return;
+#ifdef CONFIG_RT_GROUP_SCHED
/*
* Because -- for now -- we share the rt bandwidth, we need to
* account our runtime there too, otherwise actual rt tasks
@@ -1578,6 +1579,7 @@ static void update_curr_dl_se(struct rq *rq, struct sched_dl_entity *dl_se, s64
rt_rq->rt_time += delta_exec;
raw_spin_unlock(&rt_rq->rt_runtime_lock);
}
+#endif
}
/*
@@ -1633,8 +1635,7 @@ void dl_server_start(struct sched_dl_entity *dl_se)
* this before getting generic.
*/
if (!dl_server(dl_se)) {
- /* Disabled */
- u64 runtime = 0;
+ u64 runtime = 50 * NSEC_PER_MSEC;
u64 period = 1000 * NSEC_PER_MSEC;
dl_server_apply_params(dl_se, runtime, period, 1);
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 5da3297270cd..2e1f0ecdde38 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -935,9 +935,12 @@ void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq)
SEQ_printf(m, " .%-30s: %Ld.%06ld\n", #x, SPLIT_NS(rt_rq->x))
PU(rt_nr_running);
+
+#ifdef CONFIG_RT_GROUP_SCHED
P(rt_throttled);
PN(rt_time);
PN(rt_runtime);
+#endif
#undef PN
#undef PU
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 3261b067b67e..d3065fe35c61 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -8,10 +8,6 @@ int sched_rr_timeslice = RR_TIMESLICE;
/* More than 4 hours if BW_SHIFT equals 20. */
static const u64 max_rt_runtime = MAX_BW;
-static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
-
-struct rt_bandwidth def_rt_bandwidth;
-
/*
* period over which we measure -rt task CPU usage in us.
* default: 1s
@@ -67,6 +63,40 @@ static int __init sched_rt_sysctl_init(void)
late_initcall(sched_rt_sysctl_init);
#endif
+void init_rt_rq(struct rt_rq *rt_rq)
+{
+ struct rt_prio_array *array;
+ int i;
+
+ array = &rt_rq->active;
+ for (i = 0; i < MAX_RT_PRIO; i++) {
+ INIT_LIST_HEAD(array->queue + i);
+ __clear_bit(i, array->bitmap);
+ }
+ /* delimiter for bitsearch: */
+ __set_bit(MAX_RT_PRIO, array->bitmap);
+
+#if defined CONFIG_SMP
+ rt_rq->highest_prio.curr = MAX_RT_PRIO-1;
+ rt_rq->highest_prio.next = MAX_RT_PRIO-1;
+ rt_rq->overloaded = 0;
+ plist_head_init(&rt_rq->pushable_tasks);
+#endif /* CONFIG_SMP */
+ /* We start is dequeued state, because no RT tasks are queued */
+ rt_rq->rt_queued = 0;
+
+#ifdef CONFIG_RT_GROUP_SCHED
+ rt_rq->rt_time = 0;
+ rt_rq->rt_throttled = 0;
+ rt_rq->rt_runtime = 0;
+ raw_spin_lock_init(&rt_rq->rt_runtime_lock);
+#endif
+}
+
+#ifdef CONFIG_RT_GROUP_SCHED
+
+static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
+
static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
{
struct rt_bandwidth *rt_b =
@@ -131,35 +161,6 @@ static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
do_start_rt_bandwidth(rt_b);
}
-void init_rt_rq(struct rt_rq *rt_rq)
-{
- struct rt_prio_array *array;
- int i;
-
- array = &rt_rq->active;
- for (i = 0; i < MAX_RT_PRIO; i++) {
- INIT_LIST_HEAD(array->queue + i);
- __clear_bit(i, array->bitmap);
- }
- /* delimiter for bitsearch: */
- __set_bit(MAX_RT_PRIO, array->bitmap);
-
-#if defined CONFIG_SMP
- rt_rq->highest_prio.curr = MAX_RT_PRIO-1;
- rt_rq->highest_prio.next = MAX_RT_PRIO-1;
- rt_rq->overloaded = 0;
- plist_head_init(&rt_rq->pushable_tasks);
-#endif /* CONFIG_SMP */
- /* We start is dequeued state, because no RT tasks are queued */
- rt_rq->rt_queued = 0;
-
- rt_rq->rt_time = 0;
- rt_rq->rt_throttled = 0;
- rt_rq->rt_runtime = 0;
- raw_spin_lock_init(&rt_rq->rt_runtime_lock);
-}
-
-#ifdef CONFIG_RT_GROUP_SCHED
static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
{
hrtimer_cancel(&rt_b->rt_period_timer);
@@ -196,7 +197,6 @@ void unregister_rt_sched_group(struct task_group *tg)
{
if (tg->rt_se)
destroy_rt_bandwidth(&tg->rt_bandwidth);
-
}
void free_rt_sched_group(struct task_group *tg)
@@ -254,8 +254,7 @@ int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
if (!tg->rt_se)
goto err;
- init_rt_bandwidth(&tg->rt_bandwidth,
- ktime_to_ns(def_rt_bandwidth.rt_period), 0);
+ init_rt_bandwidth(&tg->rt_bandwidth, ktime_to_ns(global_rt_period()), 0);
for_each_possible_cpu(i) {
rt_rq = kzalloc_node(sizeof(struct rt_rq),
@@ -605,70 +604,6 @@ static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
return &rt_rq->tg->rt_bandwidth;
}
-#else /* !CONFIG_RT_GROUP_SCHED */
-
-static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
-{
- return rt_rq->rt_runtime;
-}
-
-static inline u64 sched_rt_period(struct rt_rq *rt_rq)
-{
- return ktime_to_ns(def_rt_bandwidth.rt_period);
-}
-
-typedef struct rt_rq *rt_rq_iter_t;
-
-#define for_each_rt_rq(rt_rq, iter, rq) \
- for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
-
-#define for_each_sched_rt_entity(rt_se) \
- for (; rt_se; rt_se = NULL)
-
-static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
-{
- return NULL;
-}
-
-static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
-{
- struct rq *rq = rq_of_rt_rq(rt_rq);
-
- if (!rt_rq->rt_nr_running)
- return;
-
- enqueue_top_rt_rq(rt_rq);
- resched_curr(rq);
-}
-
-static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
-{
- dequeue_top_rt_rq(rt_rq, rt_rq->rt_nr_running);
-}
-
-static inline int rt_rq_throttled(struct rt_rq *rt_rq)
-{
- return rt_rq->rt_throttled;
-}
-
-static inline const struct cpumask *sched_rt_period_mask(void)
-{
- return cpu_online_mask;
-}
-
-static inline
-struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
-{
- return &cpu_rq(cpu)->rt;
-}
-
-static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
-{
- return &def_rt_bandwidth;
-}
-
-#endif /* CONFIG_RT_GROUP_SCHED */
-
bool sched_rt_bandwidth_account(struct rt_rq *rt_rq)
{
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
@@ -860,7 +795,7 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
const struct cpumask *span;
span = sched_rt_period_mask();
-#ifdef CONFIG_RT_GROUP_SCHED
+
/*
* FIXME: isolated CPUs should really leave the root task group,
* whether they are isolcpus or were isolated via cpusets, lest
@@ -872,7 +807,7 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
*/
if (rt_b == &root_task_group.rt_bandwidth)
span = cpu_online_mask;
-#endif
+
for_each_cpu(i, span) {
int enqueue = 0;
struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
@@ -939,18 +874,6 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
return idle;
}
-static inline int rt_se_prio(struct sched_rt_entity *rt_se)
-{
-#ifdef CONFIG_RT_GROUP_SCHED
- struct rt_rq *rt_rq = group_rt_rq(rt_se);
-
- if (rt_rq)
- return rt_rq->highest_prio.curr;
-#endif
-
- return rt_task_of(rt_se)->prio;
-}
-
static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
{
u64 runtime = sched_rt_runtime(rt_rq);
@@ -994,6 +917,72 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
return 0;
}
+#else /* !CONFIG_RT_GROUP_SCHED */
+
+typedef struct rt_rq *rt_rq_iter_t;
+
+#define for_each_rt_rq(rt_rq, iter, rq) \
+ for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
+
+#define for_each_sched_rt_entity(rt_se) \
+ for (; rt_se; rt_se = NULL)
+
+static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
+{
+ return NULL;
+}
+
+static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
+{
+ struct rq *rq = rq_of_rt_rq(rt_rq);
+
+ if (!rt_rq->rt_nr_running)
+ return;
+
+ enqueue_top_rt_rq(rt_rq);
+ resched_curr(rq);
+}
+
+static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
+{
+ dequeue_top_rt_rq(rt_rq, rt_rq->rt_nr_running);
+}
+
+static inline int rt_rq_throttled(struct rt_rq *rt_rq)
+{
+ return false;
+}
+
+static inline const struct cpumask *sched_rt_period_mask(void)
+{
+ return cpu_online_mask;
+}
+
+static inline
+struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
+{
+ return &cpu_rq(cpu)->rt;
+}
+
+#ifdef CONFIG_SMP
+static void __enable_runtime(struct rq *rq) { }
+static void __disable_runtime(struct rq *rq) { }
+#endif
+
+#endif /* CONFIG_RT_GROUP_SCHED */
+
+static inline int rt_se_prio(struct sched_rt_entity *rt_se)
+{
+#ifdef CONFIG_RT_GROUP_SCHED
+ struct rt_rq *rt_rq = group_rt_rq(rt_se);
+
+ if (rt_rq)
+ return rt_rq->highest_prio.curr;
+#endif
+
+ return rt_task_of(rt_se)->prio;
+}
+
/*
* Update the current task's runtime statistics. Skip current tasks that
* are not in our scheduling class.
@@ -1001,7 +990,6 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
static void update_curr_rt(struct rq *rq)
{
struct task_struct *curr = rq->curr;
- struct sched_rt_entity *rt_se = &curr->rt;
s64 delta_exec;
if (curr->sched_class != &rt_sched_class)
@@ -1011,6 +999,9 @@ static void update_curr_rt(struct rq *rq)
if (unlikely(delta_exec <= 0))
return;
+#ifdef CONFIG_RT_GROUP_SCHED
+ struct sched_rt_entity *rt_se = &curr->rt;
+
if (!rt_bandwidth_enabled())
return;
@@ -1029,6 +1020,7 @@ static void update_curr_rt(struct rq *rq)
do_start_rt_bandwidth(sched_rt_bandwidth(rt_rq));
}
}
+#endif
}
static void
@@ -1185,7 +1177,6 @@ dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
static void
inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
- start_rt_bandwidth(&def_rt_bandwidth);
}
static inline
@@ -2913,19 +2904,6 @@ int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
#ifdef CONFIG_SYSCTL
static int sched_rt_global_constraints(void)
{
- unsigned long flags;
- int i;
-
- raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
- for_each_possible_cpu(i) {
- struct rt_rq *rt_rq = &cpu_rq(i)->rt;
-
- raw_spin_lock(&rt_rq->rt_runtime_lock);
- rt_rq->rt_runtime = global_rt_runtime();
- raw_spin_unlock(&rt_rq->rt_runtime_lock);
- }
- raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
-
return 0;
}
#endif /* CONFIG_SYSCTL */
@@ -2945,12 +2923,6 @@ static int sched_rt_global_validate(void)
static void sched_rt_do_global(void)
{
- unsigned long flags;
-
- raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
- def_rt_bandwidth.rt_runtime = global_rt_runtime();
- def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
- raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
}
static int sched_rt_handler(struct ctl_table *table, int write, void *buffer,
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index b200f09038db..fb8826cf80a9 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -713,13 +713,13 @@ struct rt_rq {
#endif /* CONFIG_SMP */
int rt_queued;
+#ifdef CONFIG_RT_GROUP_SCHED
int rt_throttled;
u64 rt_time;
u64 rt_runtime;
/* Nests inside the rq lock: */
raw_spinlock_t rt_runtime_lock;
-#ifdef CONFIG_RT_GROUP_SCHED
unsigned int rt_nr_boosted;
struct rq *rq;
@@ -2475,7 +2475,6 @@ extern void reweight_task(struct task_struct *p, int prio);
extern void resched_curr(struct rq *rq);
extern void resched_cpu(int cpu);
-extern struct rt_bandwidth def_rt_bandwidth;
extern void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime);
extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq);
--
2.44.0