On Wed, Oct 14, 2020 at 9:19 PM Peter Zijlstra <pet...@infradead.org> wrote:
>
> On Fri, Oct 09, 2020 at 05:25:30PM +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.
> >
> > Signed-off-by: jun qian <qianjun.ker...@gmail.com>
> > Signed-off-by: Yafang Shao <laoar.s...@gmail.com>
>
> This SoB chain isn't valid. Did Yafang's tag need to a reviewed-by or
> something?
>
This patch improves the behavior when sched_schedstat is changed from
0 to 1, so it looks good to me.
Reviewed-by: Yafang Shao <laoar.s...@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
> >
--
Thanks
Yafang
