From: Christoph Lameter <cl@linux.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
hannes@cmpxchg.org, penguin-kernel@I-love.SAKURA.ne.jp
Subject: Re: vmstat: make vmstat_updater deferrable again and shut down on idle
Date: Thu, 10 Dec 2015 19:41:08 -0600 (CST) [thread overview]
Message-ID: <alpine.DEB.2.20.1512101940230.21007@east.gentwo.org> (raw)
In-Reply-To: <20151210153118.4f39d6a4f04c96189ce015c9@linux-foundation.org>
On Thu, 10 Dec 2015, Andrew Morton wrote:
> > /*
> > + * Switch off vmstat processing and then fold all the remaining differentials
> > + * until the diffs stay at zero. The function is used by NOHZ and can only be
> > + * invoked when tick processing is not active.
> > + */
> > +void quiet_vmstat(void)
> > +{
> > + do {
> > + if (!cpumask_test_and_set_cpu(smp_processor_id(), cpu_stat_off))
> > + cancel_delayed_work(this_cpu_ptr(&vmstat_work));
> > +
> > + } while (refresh_cpu_vm_stats(false));
> > +}
>
> How do we know this will terminate in a reasonable amount of time if
> other CPUs are pounding away?
This is only dealing with the differentials of the local cpu. Other cpus
do not matter.
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next prev parent reply other threads:[~2015-12-11 1:41 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-10 20:45 Christoph Lameter
2015-12-10 23:31 ` Andrew Morton
2015-12-11 1:41 ` Christoph Lameter [this message]
2015-12-14 18:32 ` Christoph Lameter
2016-01-20 13:52 ` Shiraz Hashim
2016-01-20 15:12 ` Christoph Lameter
2016-01-21 6:24 ` Shiraz Hashim
2016-01-21 15:41 ` Christoph Lameter
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