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.kernel@xxxxxxxxx>
AuthorDate: Thu, 15 Oct 2020 14:48:46 +08:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
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.kernel@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Yafang Shao <laoar.shao@xxxxxxxxx>
Link: https://lkml.kernel.org/r/20201015064846.19809-1-qianjun.kernel@xxxxxxxxx
---
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)) {
|