linux-kernel - Re: [PATCH] sched/fair: Fix negative energy delta in find_energy_efficient

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Message-ID: <c0c99cfd-cf3d-32a1-2088-21960abae8ad@arm.com>
Date:   Fri, 30 Apr 2021 09:33:34 +0100
From:   Pierre Gondois <pierre.gondois@....com>
To:     Quentin Perret <qperret@...gle.com>
Cc:     linux-kernel@...r.kernel.org, xuewen.yan@...soc.com,
        Lukasz.Luba@....com, Vincent.Donnefort@....com,
        dietmar.eggemann@....com, qais.yousef@....com, mingo@...hat.com,
        peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, rostedt@...dmis.org,
        bsegall@...gle.com, mgorman@...e.de, bristot@...hat.com,
        qperret@...rret.net
Subject: Re: [PATCH] sched/fair: Fix negative energy delta in
 find_energy_efficient_cpu()

Hi Quentin,

I sent a v2 yesterday. This is just to answer your question:
> Not that I disagree with the approach, just being curious: do we know
> how much this is helping in practice to reduce the window by moving the
> compute_energy() calls down here?
I don't have any numbers. However, moving the computation of base_energy_pd

after looping over the CPUs of a performance domain allows to skip this 
computation

if no CPU is available in the performance domain. This should justify 
moving the

compute_energy() call.


Regards,

Pierre