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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, 9 Feb 2012 10:26:02 -0600 (CST)	[thread overview]
Message-ID: <alpine.DEB.2.00.1202091024340.32064@router.home> (raw)
In-Reply-To: <20120209155246.GD22552@somewhere.redhat.com>

On Thu, 9 Feb 2012, Frederic Weisbecker wrote:

> > 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.
>
> So this is a typical example of a timer we want to shutdown when the CPU is idle
> but we want to keep it running when we run in adaptive tickless mode (ie: shutdown
> the tick while the CPU is busy).

You can also shut it down when the cpu is busy and not doing any system
calls. If the percpu differentials are all zero (because you just ran the
timer f.e.) and there are no system activities that would change the
counters then there is no point in running the vmstat timer.


  parent reply	other threads:[~2012-02-09 16:26 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
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 [this message]
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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