linux-kernel - Re: [PATCH v2 0/2] sched: Optionally skip uclamp logic in fast path

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Date:   Wed, 24 Jun 2020 13:26:16 +0100
From:   Qais Yousef <qais.yousef@....com>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     Dietmar Eggemann <dietmar.eggemann@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Patrick Bellasi <patrick.bellasi@...bug.net>,
        Chris Redpath <chris.redpath@....com>,
        Lukasz Luba <lukasz.luba@....com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 0/2] sched: Optionally skip uclamp logic in fast path

On 06/24/20 11:00, Vincent Guittot wrote:
> On Tue, 23 Jun 2020 at 19:40, Dietmar Eggemann <dietmar.eggemann@....com> wrote:

[...]

> > (4)
> >
> > CPU0:  Function             Hit    Time            Avg             s^2
> >        --------             ---    ----            ---             ---
> >        deactivate_task  1998246    2428121 us      *1.215* us      0.062 us
> >        activate_task    1998252    2132141 us      *1.067* us      0.020 us
> >
> > CPU1:  Function             Hit    Time            Avg             s^2
> >        --------             ---    ----            ---             ---
> >        deactivate_task  1996154    2414194 us      1.209 us        0.060 us
> >        activate_task    1996148    2140667 us      1.072 us        0.021 us
> 
> I have rerun the tests that I ran previously on my octo core arm64 (hikey):
> 20 iteration of perf bench sched pipe -T -l 50000
> tip stands for tip/sched/core
> uclamp enabled means both uclamp task and uclamp cgroup
> the stdev is around 0.25% for all tests
> 
>                            root           level 1       level 2       level 3
> 
> tip uclamp disabled        50653          47188         44568         41925
> tip uclamp enabled         48800(-3.66%)  45600(-3.37%) 42822(-3.92%)
> 40257(-3.98%)
> /w patch uclamp disabled   50615(-0.08%)  47198(+0.02%) 44609(+0.09%)
> 41735(-0.45%)
> /w patch uclamp enabled    49661(-1.96%)  46611(-1.22%) 43803(-1.72%)
> 41243(-1.63%)
> 
> Results are better with your patch

Thanks both for testing!

Cheers

--
Qais Yousef