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

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Message-ID: <dbbff170-db0a-4955-a024-978bb8dc3016@meta.com>
Date: Thu, 26 Jun 2025 10:55:20 -0400
From: Chris Mason <clm@...a.com>
To: Vincent Guittot <vincent.guittot@...aro.org>
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 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?

-chris