[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <CAKc596J1eEqYjYy9dnK6VriGU6GE-7be-6Tq4VA5UUhCp3+ZMQ@mail.gmail.com>
Date: Wed, 14 Apr 2021 10:10:19 +0800
From: jun qian <qianjun.kernel@...il.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>, Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>,
Benjamin Segall <bsegall@...gle.com>,
Mel Gorman <mgorman@...e.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] sched/fair:Reduce unnecessary check preempt in the
sched tick
Peter Zijlstra <peterz@...radead.org> 于2021年4月13日周二 下午10:24写道:
>
> On Tue, Apr 13, 2021 at 09:18:42PM +0800, qianjun.kernel@...il.com wrote:
> > From: jun qian <qianjun.kernel@...il.com>
> >
> > If it has been determined that the current cpu need resched in the
> > early stage of for_each_sched_entity, then there is no need to check
> > preempt in the subsequent se->parent entity_tick.
>
> Right, but does it actually do anything, except increase linecount?
>
> > Signed-off-by: jun qian <qianjun.kernel@...il.com>
> > ---
> > kernel/sched/fair.c | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index 1a68a0536add..c0d135100d54 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -4352,8 +4352,13 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
> > {
> > unsigned long ideal_runtime, delta_exec;
> > struct sched_entity *se;
> > + struct rq *rq = rq_of(cfs_rq);
> > s64 delta;
> >
> > + /* If the TIF_NEED_RESCHED has been set, it is no need to check again */
> > + if (test_tsk_need_resched(rq->curr))
> > + return;
> > +
> > ideal_runtime = sched_slice(cfs_rq, curr);
> > delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
> > if (delta_exec > ideal_runtime) {
>
> Also, I think that's placed wrong; this way we can mis clear_buddies().
thanks, i will modify it in the next version
Powered by blists - more mailing lists