linux-kernel - Re: [RESEND RFC PATCH V3] sched: Improve scalability of select_idle

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Date:   Fri, 2 Feb 2018 21:04:01 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Steven Sistare <steven.sistare@...cle.com>
Cc:     subhra mazumdar <subhra.mazumdar@...cle.com>,
        linux-kernel@...r.kernel.org, mingo@...hat.com,
        dhaval.giani@...cle.com
Subject: Re: [RESEND RFC PATCH V3] sched: Improve scalability of
 select_idle_sibling using SMT balance

On Fri, Feb 02, 2018 at 01:34:58PM -0500, Steven Sistare wrote:
> Actually, I take back my take back.  I suspect the primary benefit
> of random selection is that it breaks up resonance states where
> CPUs that are busy tend to stay busy, and CPUs that are idle tend
> to stay idle, which is reinforced by starting the search at target =
> last cpu ran.

Which, according to there here patches:

  https://lkml.kernel.org/r/20180130104555.4125-1-mgorman@techsingularity.net

is a good thing, because of power management.