[PATCH 05/13] hperf_hmp: introduce druntime metric.

[Arseniy Krasnov]

	This patch adds special per-task metric to look for candidate for
migration between HMP domains(clusters). 'druntime' grows up when task runs on
A7 cluster, and goes down on A15 cluster. Also druntime is scaled according load
on little cluster in order to align its value with big cluster's total druntime.
For migration from big/little to little/big cluster task with lowest/highest
'druntime' chosen. 'druntime' is used to execute each task on each cluster
approximately same amount of time. 'druntime' is calculated each call of default
'update_curr' function.

Signed-off-by: Tarek Dakhran <t.dakhran@xxxxxxxxxxx>
Signed-off-by: Sergey Dyasly <s.dyasly@xxxxxxxxxxx>
Signed-off-by: Dmitriy Safonov <d.safonov@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Arseniy Krasnov <a.krasnov@xxxxxxxxxxx>
Signed-off-by: Ilya Maximets <i.maximets@xxxxxxxxxxx>
---
 include/linux/sched.h |   3 ++
 kernel/sched/core.c   |   3 ++
 kernel/sched/fair.c   | 115 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 121 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index aa72125..89c1bf3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1257,6 +1257,9 @@ struct sched_entity {
 	struct list_head	group_node;
 	unsigned int		on_rq;
 
+#ifdef CONFIG_HPERF_HMP
+	long			druntime;
+#endif
 	u64			exec_start;
 	u64			sum_exec_runtime;
 	u64			vruntime;
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 8747e06..6883a00 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2085,6 +2085,9 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
 	p->se.prev_sum_exec_runtime	= 0;
 	p->se.nr_migrations		= 0;
 	p->se.vruntime			= 0;
+#ifdef CONFIG_HPERF_HMP
+	p->se.druntime			= 0;
+#endif
 	INIT_LIST_HEAD(&p->se.group_node);
 
 #ifdef CONFIG_SCHEDSTATS
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c57007f..e94fab4 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -102,6 +102,10 @@ unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL;
 
 #ifdef CONFIG_HPERF_HMP
 extern void hmp_set_cpu_masks(struct cpumask *, struct cpumask *);
+static atomic_t a15_nr_hmp_busy = ATOMIC_INIT(0);
+static atomic_t a7_nr_hmp_busy = ATOMIC_INIT(0);
+static atomic_t hmp_imbalance = ATOMIC_INIT(0);
+
 static unsigned int freq_scale_cpu_power[CONFIG_NR_CPUS];
 #endif /* CONFIG_HPERF_HMP */
 
@@ -660,6 +664,115 @@ static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
 	return calc_delta_fair(sched_slice(cfs_rq, se), se);
 }
 
+#ifdef CONFIG_HPERF_HMP
+static bool
+is_task_hmp(struct task_struct *task, const struct cpumask *task_cpus)
+{
+	if (!task_cpus)
+		task_cpus = tsk_cpus_allowed(task);
+
+	/*
+	 * Check if a task has cpus_allowed only for one CPU domain (A15 or A7)
+	 */
+	return !(cpumask_intersects(task_cpus, cpu_fastest_mask) ^
+		 cpumask_intersects(task_cpus, cpu_slowest_mask));
+}
+
+#ifdef CONFIG_HPERF_HMP_DEBUG
+static inline void check_druntime_sum(struct rq *rq, long druntime_sum)
+{
+	BUG_ON(rq->cfs.h_nr_running == 0 && druntime_sum != 0);
+
+	if (cpu_is_fastest(rq->cpu))
+		BUG_ON(druntime_sum > 0);
+	else
+		BUG_ON(druntime_sum < 0);
+}
+#else
+static inline void check_druntime_sum(struct rq *rq, long druntime_sum)
+{
+}
+#endif
+
+static inline void add_druntime_sum(struct rq *rq, long delta)
+{
+	rq->druntime_sum += delta;
+	check_druntime_sum(rq, rq->druntime_sum);
+}
+/* Updates druntime for a task */
+static inline void
+update_hmp_stat(struct cfs_rq *cfs_rq, struct sched_entity *curr,
+		unsigned long delta_exec)
+{
+	long to_add;
+	unsigned int hmp_fairness_threshold = 240;
+	struct rq *rq = rq_of(cfs_rq);
+	int a7_nr_hmp_busy_tmp;
+
+	if (atomic_read(&hmp_imbalance) == 0)
+		return;
+
+	if (!curr->on_rq)
+		return;
+
+	if (!entity_is_task(curr))
+		return;
+
+	if (!task_of(curr)->on_rq)
+		return;
+
+	if (!cfs_rq->h_nr_running)
+		return;
+
+	if (!is_task_hmp(task_of(curr), NULL))
+		return;
+
+	delta_exec = delta_exec >> 10;
+
+	if (cpu_is_fastest(rq->cpu))
+		to_add = -delta_exec;
+	else
+		to_add = delta_exec;
+
+	to_add -= curr->druntime;
+
+	/* Avoid values with the different sign */
+	if ((cpu_is_fastest(rq->cpu) && to_add >= 0) ||
+	    (!cpu_is_fastest(rq->cpu) && to_add <= 0))
+		return;
+
+	to_add /= (long)(2 + 4 * hmp_fairness_threshold /
+			(cfs_rq->h_nr_running + 1));
+
+	a7_nr_hmp_busy_tmp = atomic_read(&a7_nr_hmp_busy);
+	/* druntime balancing between the domains */
+	if (!cpu_is_fastest(rq->cpu) && a7_nr_hmp_busy_tmp) {
+		to_add *= atomic_read(&a15_nr_hmp_busy);
+		to_add /= a7_nr_hmp_busy_tmp;
+	}
+
+	if (cpu_is_fastest(rq->cpu)) {
+		if (curr->druntime < 0)
+			add_druntime_sum(rq, to_add);
+		else if ((curr->druntime + to_add) < 0)
+			add_druntime_sum(rq, curr->druntime + to_add);
+	} else {
+		if (curr->druntime > 0)
+			add_druntime_sum(rq, to_add);
+		else if ((curr->druntime + to_add) > 0)
+			add_druntime_sum(rq, curr->druntime + to_add);
+	}
+
+	curr->druntime += to_add;
+}
+#else
+static inline void
+update_hmp_stat(struct cfs_rq *cfs_rq, struct sched_entity *curr,
+	      unsigned long delta_exec)
+{
+}
+#endif /* CONFIG_HPERF_HMP */
+
 #ifdef CONFIG_SMP
 static int select_idle_sibling(struct task_struct *p, int cpu);
 static unsigned long task_h_load(struct task_struct *p);
@@ -735,6 +848,8 @@ static void update_curr(struct cfs_rq *cfs_rq)
 	}
 
 	account_cfs_rq_runtime(cfs_rq, delta_exec);
+
+	update_hmp_stat(cfs_rq, curr, delta_exec);
 }
 
 static void update_curr_fair(struct rq *rq)
-- 
1.9.1

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