linux-kernel - Re: [PATCH] sched/fair: Optimize select_idle

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Date:   Fri, 6 Dec 2019 17:48:16 +0100
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Rik van Riel <riel@...riel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Valentin Schneider <valentin.schneider@....com>
Subject: Re: [PATCH] sched/fair: Optimize select_idle_core

On Fri, 6 Dec 2019 at 14:39, Srikar Dronamraju
<srikar@...ux.vnet.ibm.com> wrote:
>
> Hi Vincent,
>
> > >
> > > Collecting ticks on a Power 9 SMT 8 system around select_idle_core
> > > while running schbench shows us that
> > >
> > > (units are in ticks, hence lesser is better)
> > > Without patch
> > >     N           Min           Max        Median           Avg        Stddev
> > > x 130           151          1083           284     322.72308     144.41494
> > >
> > >
> > > With patch
> > >     N           Min           Max        Median           Avg        Stddev   Improvement
> > > x 164            88           610           201     225.79268     106.78943        30.03%
> >
> > Thanks for the figures. Might be good to include them in the commit message
> >
>
> Since I needed a debug/hack patch on top of upstream/my-patch to get these
> numbers, I wasn't sure if this would be ideal to be included in a commit
> message. But if you still think it's good to have, I can re-spin the patch
> with these numbers included.

IMHO, it's interesting to add figures even if you have instrumented
the code to get them

>
> > Reviewed-by: Vincent Guittot <vincent.guittot@...aro.org>
> >
>
> Thanks.
>
> --
> Thanks and Regards
> Srikar Dronamraju
>