linux-kernel - Re: [PATCH] sched/fair: don't use waker's cpu if the waker of sync wake-up is interrupt

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Message-ID: <3fe7113cc87ac89077b55ca55bda2b99729f13c8.camel@gmx.de>
Date:   Tue, 27 Apr 2021 07:54:32 +0200
From:   Mike Galbraith <efault@....de>
To:     "Song Bao Hua (Barry Song)" <song.bao.hua@...ilicon.com>,
        "vincent.guittot@...aro.org" <vincent.guittot@...aro.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "dietmar.eggemann@....com" <dietmar.eggemann@....com>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "bsegall@...gle.com" <bsegall@...gle.com>,
        "mgorman@...e.de" <mgorman@...e.de>
Cc:     "valentin.schneider@....com" <valentin.schneider@....com>,
        "juri.lelli@...hat.com" <juri.lelli@...hat.com>,
        "bristot@...hat.com" <bristot@...hat.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "xuwei (O)" <xuwei5@...wei.com>,
        "Zengtao (B)" <prime.zeng@...ilicon.com>,
        "guodong.xu@...aro.org" <guodong.xu@...aro.org>,
        yangyicong <yangyicong@...wei.com>,
        "Liguozhu (Kenneth)" <liguozhu@...ilicon.com>,
        "linuxarm@...neuler.org" <linuxarm@...neuler.org>,
        wanghuiqiang <wanghuiqiang@...wei.com>,
        "xieyongjia (A)" <xieyongjia1@...wei.com>
Subject: Re: [PATCH] sched/fair: don't use waker's cpu if the waker of sync
 wake-up is interrupt

On Tue, 2021-04-27 at 04:44 +0000, Song Bao Hua (Barry Song) wrote:
>
>
> I agree sync hint might have been overused by other kernel subsystem.
> But this patch will at least fix a case: sync waker is interrupt,
> in this case, the existing task has nothing to do with waker and wakee,
> so this case should be excluded from wake_affine_idle().

I long ago tried filtering interrupt wakeups, and met some surprises.
Wakeup twiddling always managing to end up being a rob Peter to pay
Paul operation despite our best efforts, here's hoping that your pile
of stolen cycles is small enough to escape performance bot notice :)

	-Mike