linux-kernel - Re: [PATCH] sched/fair: Fix task utilization accountability in cpu_util

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Message-ID: <66a16cf1-ffc5-2a40-7e04-900cc0e2ee2c@arm.com>
Date:   Tue, 23 Feb 2021 15:44:41 +0100
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     vincent.donnefort@....com, peterz@...radead.org, mingo@...hat.com,
        vincent.guittot@...aro.org
Cc:     linux-kernel@...r.kernel.org, qperret@...gle.com,
        patrick.bellasi@...bug.net, valentin.schneider@....com
Subject: Re: [PATCH] sched/fair: Fix task utilization accountability in
 cpu_util_next()

On 22/02/2021 10:54, vincent.donnefort@....com wrote:
> From: Vincent Donnefort <vincent.donnefort@....com>

[...]

> Also, replace sub_positive with lsub_positive which saves one explicit
> load-store.

IMHO, in case you're going to fix this now in compute_energy(), this
optimization could still be done. Maybe in an extra patch?
cpu_util_without() is using lsub_positive() to remove task util from cpu
util as well.

[...]