linux-kernel - Re: Re: [PATCH 2/2] sched/fair: Fix premature check of WAKEUP

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Message-ID: <CAKfTPtC-pSxpk9i1T4rgc8U7M-nYJ_fdJKaBJa-1dwi9+scTbg@mail.gmail.com>
Date: Tue, 25 Feb 2025 18:15:36 +0100
From: Vincent Guittot <vincent.guittot@...aro.org>
To: Abel Wu <wuyun.abel@...edance.com>
Cc: Madadi Vineeth Reddy <vineethr@...ux.ibm.com>, Peter Zijlstra <peterz@...radead.org>, 
	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>, 
	Valentin Schneider <vschneid@...hat.com>, Josh Don <joshdon@...gle.com>, 
	Tianchen Ding <dtcccc@...ux.alibaba.com>, 
	"open list:SCHEDULER" <linux-kernel@...r.kernel.org>
Subject: Re: Re: [PATCH 2/2] sched/fair: Fix premature check of WAKEUP_PREEMPTION

On Tue, 25 Feb 2025 at 07:29, Abel Wu <wuyun.abel@...edance.com> wrote:
>
> On 2/24/25 9:47 PM, Vincent Guittot wrote:
> >
> > Or we should just remove it. I'm curious to know who used it during
> > the last couple of years ? Having in mind that lazy preemption adds
>
> TBH I have never used this feature. But since Phil mentioned a case
> in debugging DELAY_DEQUEUE, I think we'd better keep it, what do you
> think?

Yes. And we need to figure out how to deal with the below as well

>
> > another level as check_preempt_wakeup_fair()  uses it so sched-idle
> > tasks might not always be immediately preempted anyway.
>
> Right, thanks for mention that.
>
> >
> >
> >>
> >> Thanks,
> >>          Abel
> >>
>