The following commit has been merged into the sched/core branch of tip: Commit-ID: b9c88f752268383beff0d56e50d52b8ae62a02f8 Gitweb: https://git.kernel.org/tip/b9c88f752268383beff0d56e50d52b8ae62a02f8 Author: jun qian <qianjun.ker...@gmail.com> AuthorDate: Thu, 15 Oct 2020 14:48:46 +08:00 Committer: Peter Zijlstra <pet...@infradead.org> CommitterDate: Thu, 29 Oct 2020 11:00:28 +01:00
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: jun qian <qianjun.ker...@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Reviewed-by: Yafang Shao <laoar.s...@gmail.com> Link: https://lkml.kernel.org/r/20201015064846.19809-1-qianjun.ker...@gmail.com --- kernel/sched/fair.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 290f9e3..b9368d1 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -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)) {
