linux-kernel - Re: [PATCH v2] sched/fair: Optimize dequeue_task

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Date:   Tue, 16 Jun 2020 15:38:55 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     Peng Wang <rocking@...ux.alibaba.com>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] sched/fair: Optimize dequeue_task_fair()

On Tue, Jun 16, 2020 at 02:31:15PM +0200, Vincent Guittot wrote:
> On Tue, 16 Jun 2020 at 08:05, Peng Wang <rocking@...ux.alibaba.com> wrote:
> >
> > While looking at enqueue_task_fair and dequeue_task_fair, it occurred
> > to me that dequeue_task_fair can also be optimized as Vincent described
> > in commit 7d148be69e3a ("sched/fair: Optimize enqueue_task_fair()").
> >
> > When encountering throttled cfs_rq, dequeue_throttle label can ensure
> > se not to be NULL, and rq->nr_running remains unchanged, so we can also
> > skip the early balance check.
> >
> > Signed-off-by: Peng Wang <rocking@...ux.alibaba.com>
> 
> Reviewed-by: Vincent Guittot <vincent.guittot@...aro.org>

Thanks!