linux-kernel - Re: [PATCH V7 0/9] SCHED_DEADLINE server infrastructure

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Message-ID: <CAO7JXPgPypC0z8SLTvt3gNndtLFaayGzh3V2uDf0D0BN1qjpEg@mail.gmail.com>
Date: Mon, 29 Jul 2024 16:42:09 -0400
From: Vineeth Remanan Pillai <vineeth@...byteword.org>
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>, Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>, 
	Daniel Bristot de Oliveira <bristot@...hat.com>, Valentin Schneider <vschneid@...hat.com>, linux-kernel@...r.kernel.org, 
	Luca Abeni <luca.abeni@...tannapisa.it>, 
	Tommaso Cucinotta <tommaso.cucinotta@...tannapisa.it>, Thomas Gleixner <tglx@...utronix.de>, 
	Joel Fernandes <joel@...lfernandes.org>, Shuah Khan <skhan@...uxfoundation.org>, 
	Phil Auld <pauld@...hat.com>, Suleiman Souhlal <suleiman@...gle.com>, 
	Youssef Esmat <youssefesmat@...gle.com>
Subject: Re: [PATCH V7 0/9] SCHED_DEADLINE server infrastructure

On Mon, Jul 29, 2024 at 6:32 AM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Fri, Jun 21, 2024 at 10:41:35AM -0400, Vineeth Remanan Pillai wrote:
>
> > Sorry that I could not get to reviewing and testing this revision. In
> > v6 we had experienced a minor bug where suspend/resume had issues with
> > dlserver. Since suspend does not do dequeue, dlserver is not stopped
> > and this causes the premature wakeups. I haven't looked at v7 in
> > detail, but I think the issue might still be present.
>
> It is not.
>
> > We have a workaround patch for this in our 5.15 kernel
>
> That is the problem... your necro kernel doesn't yet have the freezer
> rewrite I imagine:
>
>   f5d39b020809 ("freezer,sched: Rewrite core freezer logic")
>
> That would cause all frozen tasks to be dequeued, and once all tasks
> are dequeued, the deadline server stops itself too.
>
You're right, we are on 5.15 kernel and do not have this fix. Thanks
for pointing this out.

> Juri did some testing to double check and no suspend / resume issues
> were found.
>
> Anyway, I've merged the lot into tip/sched/core.
>
Thanks, I shall port it to chromeos kernel and run through the usual
round of tests and update the details soon.

Thanks,
Vineeth