linux-kernel - Re: [PATCH V1] sched: Cancel the slice protection of the idle entity

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Message-Id: <20250208082915.20842-1-15645113830zzh@gmail.com>
Date: Sat,  8 Feb 2025 16:29:16 +0800
From: zihan zhou <15645113830zzh@...il.com>
To: peterz@...radead.org
Cc: 15645113830zzh@...il.com,
	bsegall@...gle.com,
	dietmar.eggemann@....com,
	juri.lelli@...hat.com,
	linux-kernel@...r.kernel.org,
	mgorman@...e.de,
	mingo@...hat.com,
	rostedt@...dmis.org,
	vincent.guittot@...aro.org,
	vschneid@...hat.com
Subject: Re: [PATCH V1] sched: Cancel the slice protection of the idle entity

> > A wakeup non-idle entity should preempt idle entity at any time,
> > but because of the slice protection of the idle entity, the non-idle
> > entity has to wait, so just cancel it.
> > 
> > Signed-off-by: zihan zhou <15645113830zzh@...il.com>
> > ---
> >  kernel/sched/fair.c | 13 ++++++++++++-
> >  1 file changed, 12 insertions(+), 1 deletion(-)
> > 
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index 3e9ca38512de..7777d110d053 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -8851,8 +8851,19 @@ static void check_preempt_wakeup_fair(struct rq *rq, struct task_struct *p, int
> >  	 * Preempt an idle entity in favor of a non-idle entity (and don't preempt
> >  	 * in the inverse case).
> >  	 */
> > -	if (cse_is_idle && !pse_is_idle)
> > +	if (cse_is_idle && !pse_is_idle) {
> > +
> > +		/*
> > +		 * When non-idle entity preempt an idle entity,
> > +		 * don't give idle entity slice protection.
> > +		 */
> > +		if (se->vlag == se->deadline)
> > +			se->vlag = se->deadline + 1;
> > +
> >  		goto preempt;
> > +
> > +	}
> 
> Yes, I suppose we can do this.

Thank you very much for your affirmation!