linux-kernel - Re: [PATCH 2/4] sched/fair: Track efficiency of task recent_used

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Date:   Mon, 23 Mar 2020 13:30:25 +0000
From:   Valentin Schneider <valentin.schneider@....com>
To:     Mel Gorman <mgorman@...hsingularity.net>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Phil Auld <pauld@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/4] sched/fair: Track efficiency of task recent_used_cpu


On Fri, Mar 20 2020, Mel Gorman wrote:
> SIS Recent Used Hit: A recent CPU was eligible and used. Each hit is
>       a domain search avoided.
>
> SIS Recent Used Miss: A recent CPU was eligible but unavailable. Each
>       time this is hit, there was a penalty to the fast path before
>       a domain search happened.
>
> SIS Recent Success Rate: A percentage of the number of hits versus
>       the total attempts to use the recent CPU.
>
> SIS Recent Attempts: The total number of times the recent CPU was examined.
>       A high number of Recent Attempts with a low Success Rate implies
>       the fast path is being punished severely. This could have been
>       presented as a weighting of hits and misses but calculating an
>       appropriate weight for misses is problematic.
>

Ditto on the raw vs post-processed detail in the changelog, otherwise:

Reviewed-by: Valentin Schneider <valentin.schneider@....com>

> Signed-off-by: Mel Gorman <mgorman@...hsingularity.net>