linux-kernel - Re: [PATCH 1/2] x86,sched: Add support for frequency invariance

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Message-ID: <20190917143937.GA334@qperret.net>
Date:   Tue, 17 Sep 2019 16:39:37 +0200
From:   Quentin Perret <qperret@...rret.net>
To:     Giovanni Gherdovich <ggherdovich@...e.cz>
Cc:     srinivas.pandruvada@...ux.intel.com, tglx@...utronix.de,
        mingo@...hat.com, peterz@...radead.org, bp@...e.de,
        lenb@...nel.org, rjw@...ysocki.net, x86@...nel.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        mgorman@...hsingularity.net, matt@...eblueprint.co.uk,
        viresh.kumar@...aro.org, juri.lelli@...hat.com, pjt@...gle.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com
Subject: Re: [PATCH 1/2] x86,sched: Add support for frequency invariance

On Tuesday 17 Sep 2019 at 16:27:46 (+0200), Giovanni Gherdovich wrote:
> I'll check what's the cost of static_cpu_has() and if it's non-negligible I'll
> do what you suggest (x86-specific version of arch_scale_freq_invariant().

In case this is indeed expensive to check, you could always add a static
key, set at boot time, to optimize things a bit ... That might be worth
it since this is called in latency-sensitive paths of the scheduler.

Thanks,
Quentin