linux-kernel - Re: [RFC PATCH v3] tick/sched: Ensure quiet_vmstat() is called when the idle tick was stopped too

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Message-ID: <alpine.DEB.2.22.394.2204251406370.13839@gentwo.de>
Date:   Mon, 25 Apr 2022 14:09:06 +0200 (CEST)
From:   Christoph Lameter <cl@...two.de>
To:     Aaron Tomlin <atomlin@...hat.com>
cc:     frederic@...nel.org, mtosatti@...hat.com, tglx@...utronix.de,
        mingo@...nel.org, peterz@...radead.org, pauld@...hat.com,
        neelx@...hat.com, oleksandr@...alenko.name,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [RFC PATCH v3] tick/sched: Ensure quiet_vmstat() is called when
 the idle tick was stopped too

On Mon, 25 Apr 2022, Aaron Tomlin wrote:

> Yes, in the context of nohz, this patch should ensure it, if required, when
> the idle tick is to be stopped.

What I said was that it is generally useful. Even in the non NOHZ case.

Folding the vmstat diffs *always* when entering idle prevents unnecessary
wakeups and processing in the future and also provides more accurate
counters for the VM allowing better decision to be made on reclaim.