linux-kernel - find_new

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Date:   Tue, 8 Jun 2021 21:51:30 +0200 (CEST)
From:   Julia Lawall <julia.lawall@...ia.fr>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Mel Gorman <mgorman@...e.de>, linux-kernel@...r.kernel.org
Subject: find_new_ilb

Starting from the following commit:

commit 45da7a2b0af8fa29dff2e6ba8926322068350fce
Author: Peter Zijlstra <peterz@...radead.org>
Date:   Tue Aug 18 10:48:17 2020 +0200

    sched/fair: Exclude the current CPU from find_new_ilb()

up through Linux 5.12, I observed that often when most of the machine was
idle, there could be many (thousands) of sched_wake_idle_without_ipi
events, typically between cores 0 and 1.  I don't see this any more in
Linux v5.13-rc1.  I looked through the patches to fair.c and core.c
subsequent to v5.12, and I didn't see anything that explicitly addresses
this issue.  Before I plunge into another set of rounds of bisecting, I
wonder if anyone knows whether and how this problem was resolved?

thanks,
julia