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Commit c976a862 authored by Viresh Kumar's avatar Viresh Kumar Committed by Ingo Molnar
Browse files

sched/fair: Avoid calling sync_entity_load_avg() unnecessarily 



Call sync_entity_load_avg() directly from find_idlest_cpu() instead of
select_task_rq_fair(), as that's where we need to use task's utilization
value. And call sync_entity_load_avg() only after making sure sched
domain spans over one of the allowed CPUs for the task.

Signed-off-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/cd019d1753824c81130eae7b43e2bbcec47cc1ad.1524738578.git.viresh.kumar@linaro.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent f1d88b44

kernel/sched/fair.c

+7 −9
Original line number Diff line number Diff line
@@ -6199,6 +6199,13 @@ static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p 
	if (!cpumask_intersects(sched_domain_span(sd), &p->cpus_allowed))

		return prev_cpu;



	/*

	 * We need task's util for capacity_spare_wake, 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;
@@ -6651,15 +6658,6 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f 


	if (unlikely(sd)) {

		/* Slow path */



		/*

		 * We're going to need the task's util for capacity_spare_wake

		 * in find_idlest_group. Sync it up to prev_cpu's

		 * last_update_time.

		 */

		if (!(sd_flag & SD_BALANCE_FORK))

			sync_entity_load_avg(&p->se);



		new_cpu = find_idlest_cpu(sd, p, cpu, prev_cpu, sd_flag);

	} else if (sd_flag & SD_BALANCE_WAKE) { /* XXX always ? */

		/* Fast path */