Commit b9c88f75 authored by jun qian's avatar jun qian Committed by Peter Zijlstra
Browse files

sched/fair: Improve the accuracy of sched_stat_wait statistics 



When the sched_schedstat changes from 0 to 1, some sched se maybe
already in the runqueue, the se->statistics.wait_start will be 0.
So it will let the (rq_of(cfs_rq)) - se->statistics.wait_start)
wrong. We need to avoid this scenario.

Signed-off-by: default avatarjun qian <qianjun.kernel@gmail.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarYafang Shao <laoar.shao@gmail.com>
Link: https://lkml.kernel.org/r/20201015064846.19809-1-qianjun.kernel@gmail.com
parent 23859ae4

kernel/sched/fair.c

+9 −0
Original line number Diff line number Diff line
@@ -906,6 +906,15 @@ update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se) 
	if (!schedstat_enabled())

		return;



	/*

	 * When the sched_schedstat changes from 0 to 1, some sched se

	 * maybe already in the runqueue, the se->statistics.wait_start

	 * will be 0.So it will let the delta wrong. We need to avoid this

	 * scenario.

	 */

	if (unlikely(!schedstat_val(se->statistics.wait_start)))

		return;



	delta = rq_clock(rq_of(cfs_rq)) - schedstat_val(se->statistics.wait_start);



	if (entity_is_task(se)) {