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Date: Fri, 11 May 2012 19:24:31 -0400
From: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
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Subject: Re: Allow migration of mlocked page?
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To: Christoph Lameter <cl@linux.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Minchan Kim <minchan@kernel.org>, Johannes Weiner <hannes@cmpxchg.org>, Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>, Andrew Morton <akpm@linux-foundation.org>, Andrea Arcangeli <aarcange@redhat.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, "linux-mm@kvack.org" <linux-mm@kvack.org>, tglx@linutronix.de, Ingo Molnar <mingo@redhat.com>, Theodore Ts'o <tytso@mit.edu>, kosaki.motohiro@gmail.com

(5/11/12 12:20 PM), Christoph Lameter wrote:
> On Fri, 11 May 2012, Peter Zijlstra wrote:
>
>> On Fri, 2012-05-11 at 13:37 +0900, Minchan Kim wrote:
>>> I hope hear opinion from rt guys, too.
>>
>> Its a problem yes, not sure your solution is any good though. As it
>> stands mlock() simply doesn't guarantee no faults, all it does is
>> guarantee no major faults.
>
> There are two different way to lock pages down in memory that have
> different counters in /proc/<pid>/status and also different semantics.
>
> VmLck: Mlocked pages. This means there is a prohibition against evicting
> pages. These pages can undergo page migration and therefore also be
> handled by compation. These pages have PG_mlock set.
>
> VmPin: Pinned pages. Page cannot be moved. These pages have an elevated
> refcount that makes page migration fail.

I don't see VmPin counter in my box. Did you introduce this one recently?


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