linux-kernel - Re: [PATCH v2 2/2] sched

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Message-ID: <CAKfTPtB=77c-RsJ23suNZVf7qByeGSjYQJbiEU4JpXU6DezNLQ@mail.gmail.com>
Date: Mon, 8 Jul 2024 21:51:08 +0200
From: Vincent Guittot <vincent.guittot@...aro.org>
To: Tejun Heo <tj@...nel.org>
Cc: rafael@...nel.org, viresh.kumar@...aro.org, linux-pm@...r.kernel.org, 
	void@...ifault.com, linux-kernel@...r.kernel.org, kernel-team@...a.com, 
	mingo@...hat.com, peterz@...radead.org, David Vernet <dvernet@...a.com>, 
	"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH v2 2/2] sched_ext: Add cpuperf support

On Mon, 8 Jul 2024 at 20:20, Tejun Heo <tj@...nel.org> wrote:
>
> Hello, Vincent.
>
> On Mon, Jul 08, 2024 at 08:37:06AM +0200, Vincent Guittot wrote:
> > I prefer to minimize (if not remove) sched_ext related calls in the
> > fair path so we can easily rework it if needed. And this will also
> > ensure that all fair task are cleanly removed when they are all
> > switched to sched_ext
>
> Unless we add a WARN_ON_ONCE, if it doesn't behave as expected, the end
> result will most likely be cpufreq sometimes picking a higher freq than
> requested, which won't be the easiest to notice. Would you be against adding
> WARN_ON_ONCE(scx_switched_all && !util) too?

A WARN_ON_ONCE to detect misbehavior would be ok

>
> Thanks.
>
> --
> tejun