Messages in this thread Patch in this message | | | From | qianjun.kernel@gmail ... | Subject | [PATCH 1/1] Sched/fair: Improve the accuracy of sched_stat_wait statistics | Date | Fri, 9 Oct 2020 17:25:30 +0800 |
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From: jun qian <qianjun.kernel@gmail.com>
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.kernel@gmail.com> Signed-off-by: Yafang Shao <laoar.shao@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 1a68a05..6f8ca0c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -906,6 +906,15 @@ static void update_curr_fair(struct rq *rq) 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)) { -- 1.8.3.1
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