linux-kernel - Re: [PATCH v4 5/6] x86,sched: Add support for frequency invariance on ATOM

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Date:   Fri, 15 Nov 2019 11:34:21 +0100
From:   Giovanni Gherdovich <ggherdovich@...e.cz>
To:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...e.de>, Len Brown <lenb@...nel.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>
Cc:     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 5/6] x86,sched: Add support for frequency invariance
 on ATOM

On Wed, 2019-11-13 at 08:50 -0800, Srinivas Pandruvada wrote:
> On Wed, 2019-11-13 at 13:46 +0100, Giovanni Gherdovich wrote:
> > The scheduler needs the ratio freq_curr/freq_max for frequency-
> > invariant
> > accounting. On all ATOM CPUs prior to Goldmont, set freq_max to the
> > 1-core
> > turbo ratio.
> > 
> > We intended to perform tests validating that this patch doesn't
> > regress in
> > terms of energy efficiency, given that this is the primary concern on
> > Atom
> > processors. Alas, we found out that turbostat doesn't support reading
> > RAPL
> > interfaces on our test machine (Airmont), and we don't have external
> > equipment
> > to measure power consumption; all we have is the performance results
> > of the
> > benchmarks we ran.
> > 
> 
> I can run some benchmarks on this.
> 

That'd be appreciated, thank you Srinivas.


Giovanni