linux-kernel - Re: [PATCH RFC] sched/fair: bump sd->max_newidle_lb

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Message-ID: <CAKfTPtBinqRvLk4bvP4bbEZU1OcGV=DBnyxQ2SO9SumdwfV-aA@mail.gmail.com>
Date: Fri, 27 Jun 2025 15:32:32 +0200
From: Vincent Guittot <vincent.guittot@...aro.org>
To: Chris Mason <clm@...a.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Chris Mason <clm@...com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] sched/fair: bump sd->max_newidle_lb_cost when newidle
 balance fails

On Thu, 26 Jun 2025 at 16:55, Chris Mason <clm@...a.com> wrote:
>
> On 6/26/25 10:26 AM, Vincent Guittot wrote:
> > On Thu, 26 Jun 2025 at 12:58, Chris Mason <clm@...a.com> wrote:
>
> >> Got it, I'll play with that.  Vincent, was there a benchmark I can use
> >> to see if I've regressed the case you were focused on?
> >
> > It's not a public benchmark but I had some unitary tests with tasks
> > waiting on a busy CPU while other CPUs become idle for a "long" time
> > (but still less than 500us in average). This is even more true with
> > frequency scaling which will minimize the idle duration by decreasing
> > the frequency
>
> Ok, I don't think I'll be able to reliably recreate that on my own, can
> I ask you to rerun against the v2 I sent out?

Yes, I will run some tests

Vincent

>
> -chris