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Date: Tue, 20 Mar 2012 13:48:19 +0200
From: Avi Kivity <avi@redhat.com>
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Subject: Re: [RFC][PATCH 00/26] sched/numa
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To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>, Paul Turner <pjt@google.com>, Suresh Siddha <suresh.b.siddha@intel.com>, Mike Galbraith <efault@gmx.de>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Lai Jiangshan <laijs@cn.fujitsu.com>, Dan Smith <danms@us.ibm.com>, Bharata B Rao <bharata.rao@gmail.com>, Lee Schermerhorn <Lee.Schermerhorn@hp.com>, Andrea Arcangeli <aarcange@redhat.com>, Rik van Riel <riel@redhat.com>, Johannes Weiner <hannes@cmpxchg.org>, linux-kernel@vger.kernel.org, linux-mm@kvack.org

On 03/20/2012 01:07 PM, Peter Zijlstra wrote:
> On Tue, 2012-03-20 at 12:52 +0200, Avi Kivity wrote:
>
> > You use the dma engine for eager copying, not on demand.
>
> Sure, but during that time no access to that entire vma is allowed, so
> you have to unmap it, and any fault in there will have to wait for the
> entire copy to complete.
>
> Or am I misunderstanding how things would work?

Option 1: write-protect the area you are migrating, on write fault allow
write access and discard the migration target (marking the page for
migration later)

Option 2: clear the dirty bits on the area you are migrating, after
migration completes examine the dirty bit, and if dirty, discard the
migration target.

-- 
error compiling committee.c: too many arguments to function

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