Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 9674f5ca authored by Viresh Kumar's avatar Viresh Kumar Committed by Ingo Molnar
Browse files

sched/fair: Avoid checking cfs_rq->nr_running twice 



Rearrange pick_next_task_fair() a bit to avoid checking
cfs_rq->nr_running twice for the case where FAIR_GROUP_SCHED is enabled
and the previous task doesn't belong to the fair class.

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>
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/000903ab3df3350943d3271c53615893a230dc95.1495603536.git.viresh.kumar@linaro.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent c7132dd6

kernel/sched/fair.c

+9 −7
Original line number Diff line number Diff line
@@ -6187,10 +6187,10 @@ pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf 
	int new_tasks;



again:

#ifdef CONFIG_FAIR_GROUP_SCHED

	if (!cfs_rq->nr_running)

		goto idle;



#ifdef CONFIG_FAIR_GROUP_SCHED

	if (prev->sched_class != &fair_sched_class)

		goto simple;
@@ -6220,12 +6220,18 @@ pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf 
			/*

			 * This call to check_cfs_rq_runtime() will do the

			 * throttle and dequeue its entity in the parent(s).

			 * Therefore the 'simple' nr_running test will indeed

			 * Therefore the nr_running test will indeed

			 * be correct.

			 */

			if (unlikely(check_cfs_rq_runtime(cfs_rq)))

			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, curr);

		cfs_rq = group_cfs_rq(se);
@@ -6264,12 +6270,8 @@ pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf 


	return p;

simple:

	cfs_rq = &rq->cfs;

#endif



	if (!cfs_rq->nr_running)

		goto idle;



	put_prev_task(rq, prev);



	do {