linux-kernel - Re: [PATCH 3/6] sched: Simplify sched_info

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Date:   Wed, 12 May 2021 13:51:29 +0100
From:   Mel Gorman <mgorman@...e.de>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     tglx@...utronix.de, mingo@...nel.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, bristot@...hat.com,
        bsingharora@...il.com, pbonzini@...hat.com, maz@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        riel@...riel.com, hannes@...xchg.org
Subject: Re: [PATCH 3/6] sched: Simplify sched_info_on()

On Wed, May 12, 2021 at 01:32:03PM +0200, Peter Zijlstra wrote:
> On Wed, May 12, 2021 at 12:10:40PM +0100, Mel Gorman wrote:
> > As delta is !0 iff t->sched_info.last_queued, why not this?
> > 
> > diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
> > index 33ffd41935ba..37e33c0eeb7c 100644
> > --- a/kernel/sched/stats.h
> > +++ b/kernel/sched/stats.h
> > @@ -158,15 +158,14 @@ static inline void psi_sched_switch(struct task_struct *prev,
> >   */
> >  static inline void sched_info_dequeue(struct rq *rq, struct task_struct *t)
> >  {
> > -	unsigned long long delta = 0;
> > -
> >  	if (t->sched_info.last_queued) {
> > +		unsigned long long delta;
> > +
> >  		delta = rq_clock(rq) - t->sched_info.last_queued;
> >  		t->sched_info.last_queued = 0;
> > +		t->sched_info.run_delay += delta;
> > +		rq_sched_info_dequeue(rq, delta);
> >  	}
> > -	t->sched_info.run_delay += delta;
> > -
> > -	rq_sched_info_dequeue(rq, delta);
> >  }
> 
> Right.. clearly I missed the obvious there.. Lemme go add another patch
> on top of the lot.
> 
> Something like this I suppose.
> 

That works for me.

-- 
Mel Gorman
SUSE Labs