linux-kernel - Re: [PATCH V3 1/2] sched: Reduce the default slice to avoid tasks getting an extra tick

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Message-ID: <CAKfTPtCLg_kuRtknPsiLwRdKpvb4CYHqv+BRh5yJV8Z+o4oQcw@mail.gmail.com>
Date: Mon, 24 Feb 2025 15:15:57 +0100
From: Vincent Guittot <vincent.guittot@...aro.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Qais Yousef <qyousef@...alina.io>, zihan zhou <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, vschneid@...hat.com
Subject: Re: [PATCH V3 1/2] sched: Reduce the default slice to avoid tasks
 getting an extra tick

On Mon, 10 Feb 2025 at 10:13, Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Mon, Feb 10, 2025 at 01:29:31AM +0000, Qais Yousef wrote:
>
> > I brought the topic up of these magic values with Peter and Vincent in LPC as
> > I think this logic is confusing. I have nothing against your patch, but if the
> > maintainers agree I am in favour of removing it completely in favour of setting
> > it to a single value that is the same across all systems.
>
> You're talking about the scaling, right?
>
> Yeah, it is of limited use. The cap at 8, combined with the fact that
> its really hard to find a machine with less than 8 CPUs on, makes the
> whole thing mostly useless.
>
> Back when we did this, we still had dual-core laptops. Now phones have
> 8 or more CPUs on.
>
> So I don't think I mind ripping it out.

Beside the question of ripping it out or not. We still have a number
of devices with less than 8 cores but they are not targeting phones,
laptops or servers ...