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From: Peter Zijlstra <peterz@infradead.org>
To: Christoph Lameter <cl@linux.com>
Cc: Rik van Riel <riel@redhat.com>,
	mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org,
	torvalds@linux-foundation.org, pjt@google.com,
	bharata.rao@gmail.com, akpm@linux-foundation.org,
	Lee.Schermerhorn@hp.com, aarcange@redhat.com, danms@us.ibm.com,
	suresh.b.siddha@intel.com, tglx@linutronix.de,
	linux-tip-commits@vger.kernel.org
Subject: Re: [tip:sched/numa] sched/numa: Introduce sys_numa_{t,m}bind()
Date: Fri, 18 May 2012 18:04:01 +0200	[thread overview]
Message-ID: <1337357041.573.86.camel@twins> (raw)
In-Reply-To: <alpine.DEB.2.00.1205181057400.21093@router.home>

On Fri, 2012-05-18 at 11:00 -0500, Christoph Lameter wrote:

> Having the page local is a win if there are a sufficient number of
> accesses to amortize the effort to move the page. Given the expensive
> nature of page migration there would need to be a large number of accesses
> to a page to justify the effort.

Right, but this is true of any migration scheme and not specific to MoF.

> > How does it matter how you migrate?
> 
> Migrate on fault incurs two types of costs:
> 
> 1. Unmapping. This results in additional faults to reestablish the ptes.
> 
> 2. Actual lazy migrate. More faults. Now the page needs to be copied to
>    the new node and the actual migration work is done. 

Nah, only the 1 fault is extra. Regular migration already needs to unmap
and copy and reinstate, so the only extra work is the fault to trigger
it.





  reply	other threads:[~2012-05-18 16:04 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-18 10:42 [tip:sched/numa] sched/numa: Introduce sys_numa_{t,m}bind() tip-bot for Peter Zijlstra
2012-05-18 15:14 ` Rik van Riel
2012-05-18 15:25   ` Christoph Lameter
2012-05-18 15:33     ` Peter Zijlstra
2012-05-18 15:37       ` Christoph Lameter
2012-05-18 15:47         ` Peter Zijlstra
2012-05-18 15:35   ` Peter Zijlstra
2012-05-18 15:40     ` Peter Zijlstra
2012-05-18 15:47       ` Christoph Lameter
2012-05-18 15:49         ` Peter Zijlstra
2012-05-18 16:00           ` Christoph Lameter
2012-05-18 16:04             ` Peter Zijlstra [this message]
2012-05-18 16:07               ` Christoph Lameter
2012-05-18 15:48     ` Rik van Riel
2012-05-18 16:05       ` Peter Zijlstra
2012-05-19 11:19         ` Ingo Molnar
2012-05-19 11:09     ` Ingo Molnar
2012-05-19 10:32   ` Pekka Enberg
2012-05-20  2:23 ` David Rientjes
2012-05-21  8:40   ` Ingo Molnar
2012-05-22  2:16     ` David Rientjes
2012-05-22  2:42       ` David Rientjes
2012-05-22 12:04         ` Peter Zijlstra
2012-05-22 15:00           ` Peter Zijlstra
2012-05-23 16:00             ` Peter Zijlstra
2012-05-24  0:58               ` David Rientjes
2012-05-25  8:35                 ` Peter Zijlstra
2012-05-31 22:03                   ` Peter Zijlstra
2012-05-30 13:37               ` [tip:sched/urgent] sched: Fix SD_OVERLAP tip-bot for Peter Zijlstra
2012-05-30 13:38           ` [tip:sched/urgent] sched: Make sure to not re-read variables after validation tip-bot for Peter Zijlstra

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