linux-kernel - Re: [PATCH v4 1/6] x86,sched: Add support for frequency invariance

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Message-ID: <20191218193429.GH11457@worktop.programming.kicks-ass.net>
Date:   Wed, 18 Dec 2019 20:34:29 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Giovanni Gherdovich <ggherdovich@...e.cz>
Cc:     Ionela Voinescu <ionela.voinescu@....com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...e.de>,
        Len Brown <lenb@...nel.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>, x86@...nel.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Mel Gorman <mgorman@...hsingularity.net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Paul Turner <pjt@...gle.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Quentin Perret <qperret@...rret.net>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Doug Smythies <dsmythies@...us.net>
Subject: Re: [PATCH v4 1/6] x86,sched: Add support for frequency invariance

On Fri, Dec 06, 2019 at 12:57:46PM +0100, Giovanni Gherdovich wrote:
> > On Wednesday 13 Nov 2019 at 13:46:49 (+0100), Giovanni Gherdovich wrote:
> > I see above that you enable the static key (and therefore frequency
> > invariance before setting the max frequency ratio (if possible) and
> > before you initialise the counter references. Is there any reason for
> > doing this?

> This is a fair point; mine was a deliberate choice but you're the second
> person making this remark (Peter Zijlstra also suggested I find the max
> frequency before I set the static key), so it appears this design is
> unpopular
> enough to warrant a change in v5.

You actually 'fix' this in the next patch. I thought it was a patch
management 'fail' that it didn't end up in this patch.