linux-kernel - Re: [PATCH] sched/debug: Add new tracepoints to track util

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Message-ID: <jhjlfl4icdx.mognet@arm.com>
Date:   Wed, 03 Jun 2020 13:04:26 +0100
From:   Valentin Schneider <valentin.schneider@....com>
To:     vincent.donnefort@....com
Cc:     mingo@...hat.com, peterz@...radead.org, vincent.guittot@...aro.org,
        linux-kernel@...r.kernel.org, patrick.bellasi@...bug.net,
        dietmar.eggemann@....com, qais.yousef@....com
Subject: Re: [PATCH] sched/debug: Add new tracepoints to track util_est


On 27/05/20 17:39, vincent.donnefort@....com wrote:
> From: Vincent Donnefort <vincent.donnefort@....com>
>
> The util_est signals are key elements for EAS task placement and
> frequency selection. Having tracepoints to track these signals enables
> load-tracking and schedutil testing and/or debugging by a toolkit.
>
> Signed-off-by: Vincent Donnefort <vincent.donnefort@....com>
>

To put it more bluntly, we can't really do task placement / load tracking
testing if util_est is enabled (which reminds me we may want to get rid of
the SCHED_FEAT at some point, it's been default on since ~v4.17), since
there can be noticeable gaps between util_avg and util_est.

Reviewed-by: Valentin Schneider <valentin.schneider@....com>