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

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Message-ID: <20220224130148.xfpfmybrtayjncor@ava.usersys.com>
Date:   Thu, 24 Feb 2022 13:01:48 +0000
From:   Aaron Tomlin <atomlin@...mlin.com>
To:     Marcelo Tosatti <mtosatti@...hat.com>
Cc:     Frederic Weisbecker <frederic@...nel.org>,
        Christoph Lameter <cl@...ux.com>, tglx@...utronix.de,
        mingo@...nel.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Phil Auld <pauld@...hat.com>
Subject: Re: [RFC PATCH] tick/sched: Ensure quiet_vmstat() is called when the
 idle tick was stopped too

On Thu 2022-02-24 09:30 -0300, Marcelo Tosatti wrote:
> > > > > 2) What if we are running task A in kernel mode while the tick is stopped
> > > > >    (nohz_full). Task A modifies the vmstat and goes to userspace for a long
> > > > >    while.
> > > > > Your patch fixes case 1) but not case 2). The problem is that TIMER_DEFERRABLE
> > > > > should really be about dynticks-idle only and not dynticks-full. I've always
> > > > > been afraid about enforcing that rule though because that would break old
> > > > > noise-free setups. But perhaps I should...
> 
> Can't grasp the sentence above "The problem is that ...".
> What rule?

Hi Marcelo,

That statement was from Frederic.


Kind regards,

-- 
Aaron Tomlin