On Wed, Sep 30, 2020 at 10:47:12AM +0800, qianjun.ker...@gmail.com wrote:
> From: jun qian <qianjun.ker...@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.
Is this really the only problem there? Did you do a full audit of that
schedstat nonsense?
> Signed-off-by: jun qian <qianjun.ker...@gmail.com>
> Signed-off-by: Yafang Shao <laoar.s...@gmail.com>
> ---
> kernel/sched/fair.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 658aa7a..dd7c3bb 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -908,6 +908,14 @@ static void update_curr_fair(struct rq *rq)
your git-diff is 'funny', it got the function ^ wrong.
> 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
>
