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From: Christoph Lameter <cl@linux.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Gilad Ben-Yossef <gilad@benyossef.com>, Tejun Heo <tj@kernel.org>,
	John Stultz <johnstul@us.ibm.com>,
	Mike Frysinger <vapier@gentoo.org>,
	Minchan Kim <minchan.kim@gmail.com>,
	Hakan Akkan <hakanakkan@gmail.com>,
	Max Krasnyansky <maxk@qualcomm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Linux-MM <linux-mm@kvack.org>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: RFC vmstat: On demand vmstat threads
Date: Mon, 23 Sep 2013 15:10:07 +0000	[thread overview]
Message-ID: <000001414b5ebafe-a82f870f-283a-4210-a1d8-4035e2720c4f-000000@email.amazonses.com> (raw)
In-Reply-To: <alpine.DEB.2.02.1309201930590.4089@ionos.tec.linutronix.de>

On Fri, 20 Sep 2013, Thomas Gleixner wrote:

> Now when a cpu becomes isolated we stop the callback scheduling on
> that cpu and assign it to the cpu with the smallest NUMA
> distance. So that cpu will process the data for itself and for the
> newly isolated cpu.

That is not possible for many percpu threads since they rely on running on
a specific cpu for optimization purposes. Running on a different processor
makes these threads racy.

What is needed is to be able to switch these things off and on. Something
on a different cpu may monitor if processing on that specific cpu is
needed or not but it cannot perform the vmstat updates.

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  reply	other threads:[~2013-09-23 15:16 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-04 16:48 Christoph Lameter
2013-09-10  6:15 ` Gilad Ben-Yossef
2013-09-10 21:13   ` Christoph Lameter
2013-09-18 22:06     ` Andrew Morton
2013-09-18 22:57       ` Thomas Gleixner
2013-09-19 18:58         ` Christoph Lameter
2013-09-20 10:41           ` Thomas Gleixner
2013-09-20 16:42             ` Frederic Weisbecker
2013-09-20 21:03               ` Thomas Gleixner
2013-09-23 15:10                 ` Christoph Lameter [this message]
2013-09-23 15:03             ` Christoph Lameter
2013-09-19 16:54       ` Gilad Ben-Yossef
2013-09-19 21:42     ` Gilad Ben-Yossef

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