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From: Christoph Lameter <cl@linux.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Gilad Ben-Yossef <gilad@benyossef.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	linux-kernel@vger.kernel.org, Chris Metcalf <cmetcalf@tilera.com>,
	linux-mm@kvack.org, Pekka Enberg <penberg@kernel.org>,
	Matt Mackall <mpm@selenic.com>,
	Sasha Levin <levinsasha928@gmail.com>,
	Rik van Riel <riel@redhat.com>, Andi Kleen <andi@firstfloor.org>,
	Mel Gorman <mel@csn.ul.ie>,
	Andrew Morton <akpm@linux-foundation.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Avi Kivity <avi@redhat.com>,
	Michal Nazarewicz <mina86@mina86.com>,
	Kosaki Motohiro <kosaki.motohiro@gmail.com>,
	Milton Miller <miltonm@bga.com>
Subject: Re: [v7 0/8] Reduce cross CPU IPI interference
Date: Thu, 2 Feb 2012 10:29:57 -0600 (CST)	[thread overview]
Message-ID: <alpine.DEB.2.00.1202021028120.6221@router.home> (raw)
In-Reply-To: <20120202162420.GE9071@somewhere.redhat.com>

[-- Attachment #1: Type: TEXT/PLAIN, Size: 1072 bytes --]

On Thu, 2 Feb 2012, Frederic Weisbecker wrote:

> > Some pinned timers might be able to get special treatment as well - take for
> > example the vmstat work being schedule every second, what should we do with
> > it for CPU isolation?
>
> Right, I remember I saw these vmstat timers on my way when I tried to get 0
> interrupts on a CPU.
>
> I think all these timers need to be carefully reviewed before doing anything.
> But we certainly shouldn't adopt the behaviour of migrating timers by default.
>
> Some timers really needs to stay on the expected CPU. Note that some
> timers may be shutdown by CPU hotplug callbacks. Those wouldn't be migrated
> in case of CPU offlining. We need to keep them.
>
> > It makes sense to me to have that stop scheduling itself when we have the tick
> > disabled for both idle and a nohz task.

The vmstat timer only makes sense when the OS is doing something on the
processor. Otherwise if no counters are incremented and the page and slab
allocator caches are empty then there is no need to run the vmstat timer.

  reply	other threads:[~2012-02-02 16:30 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-26 10:01 [v7 0/8] Reduce cross CPU IPI interference Gilad Ben-Yossef
2012-01-26 10:01 ` [v7 1/8] smp: introduce a generic on_each_cpu_mask function Gilad Ben-Yossef
2012-01-29 12:24   ` Gilad Ben-Yossef
2012-01-30 21:52     ` Andrew Morton
2012-01-31  6:33       ` Gilad Ben-Yossef
2012-01-26 10:01 ` [v7 2/8] arm: move arm over to generic on_each_cpu_mask Gilad Ben-Yossef
2012-01-26 10:01 ` [v7 3/8] tile: move tile to use " Gilad Ben-Yossef
2012-01-26 10:01 ` [v7 4/8] smp: add func to IPI cpus based on parameter func Gilad Ben-Yossef
2012-01-27 23:57   ` Andrew Morton
2012-01-29 12:04     ` Gilad Ben-Yossef
2012-01-26 10:01 ` [v7 5/8] slub: only IPI CPUs that have per cpu obj to flush Gilad Ben-Yossef
2012-01-26 15:09   ` Christoph Lameter
2012-01-26 10:01 ` [v7 6/8] fs: only send IPI to invalidate LRU BH when needed Gilad Ben-Yossef
2012-01-26 10:02 ` [v7 7/8] mm: only IPI CPUs to drain local pages if they exist Gilad Ben-Yossef
2012-01-26 15:13   ` Christoph Lameter
2012-01-28  0:12   ` Andrew Morton
2012-01-29 12:18     ` Gilad Ben-Yossef
2012-01-30 21:49       ` Andrew Morton
2012-01-31  6:32         ` Gilad Ben-Yossef
2012-01-30 14:59   ` Mel Gorman
2012-01-30 15:14     ` Gilad Ben-Yossef
2012-01-30 15:44       ` Mel Gorman
2012-01-26 10:02 ` [v7 8/8] mm: add vmstat counters for tracking PCP drains Gilad Ben-Yossef
2012-01-26 15:19 ` [v7 0/8] Reduce cross CPU IPI interference Peter Zijlstra
2012-01-29  8:25   ` Gilad Ben-Yossef
2012-02-01 17:04     ` Frederic Weisbecker
2012-02-02  8:46       ` Gilad Ben-Yossef
2012-02-02 15:41         ` Chris Metcalf
2012-02-05 11:46           ` Gilad Ben-Yossef
2012-02-10 18:39             ` Peter Zijlstra
2012-02-10 20:13               ` Gilad Ben-Yossef
2012-02-10 20:29                 ` Peter Zijlstra
2012-02-10 20:39                   ` Gilad Ben-Yossef
2012-02-10 18:33           ` Peter Zijlstra
2012-02-10 20:33             ` Gilad Ben-Yossef
2012-02-15 21:50             ` Chris Metcalf
2012-02-15 22:15               ` Christoph Lameter
2012-02-15 23:44                 ` Chris Metcalf
2012-02-21  1:34               ` Frederic Weisbecker
2012-03-01 18:27                 ` Chris Metcalf
2012-02-10 18:38           ` Peter Zijlstra
2012-02-10 20:24             ` Gilad Ben-Yossef
2012-02-15 15:11               ` Peter Zijlstra
2012-02-15 15:19                 ` Gilad Ben-Yossef
2012-02-15 21:51               ` Chris Metcalf
2012-02-02 16:24         ` Frederic Weisbecker
2012-02-02 16:29           ` Christoph Lameter [this message]
2012-02-09 15:52             ` Frederic Weisbecker
2012-02-09 15:59               ` Chris Metcalf
2012-02-09 18:11                 ` Frederic Weisbecker
2012-02-09 16:26               ` Christoph Lameter
2012-02-09 18:32                 ` Frederic Weisbecker
2012-02-01 17:35     ` Peter Zijlstra
2012-02-01 17:57       ` Peter Zijlstra
2012-02-02  9:42         ` Gilad Ben-Yossef
2012-02-01 18:40       ` Paul E. McKenney
2012-02-01 20:06         ` Christoph Lameter
2012-02-01 20:13           ` Paul E. McKenney
2012-02-02  9:34             ` Avi Kivity
2012-02-02 15:34               ` Paul E. McKenney
2012-02-02 16:14                 ` Avi Kivity
2012-02-02 17:01                   ` Paul E. McKenney
2012-02-02 17:23                     ` Avi Kivity
2012-02-02 17:51                       ` Paul E. McKenney
2012-02-05 12:16                         ` Avi Kivity
2012-02-05 16:59                           ` Paul E. McKenney
2012-02-09 15:22                             ` Frederic Weisbecker
2012-02-09 16:05                               ` Avi Kivity
2012-02-09 18:22                                 ` Frederic Weisbecker
2012-02-09 23:41                                   ` Paul E. McKenney
2012-02-10  1:39                                     ` Frederic Weisbecker
2012-02-14 13:18                                       ` Avi Kivity
2012-02-21  0:02                                         ` Frederic Weisbecker
2012-02-02 17:25                     ` Christoph Lameter
2012-02-05 12:06                       ` Gilad Ben-Yossef
2012-02-06 18:19                         ` Christoph Lameter
2012-02-09 15:37                           ` Frederic Weisbecker

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