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Date: Wed, 23 Nov 2011 15:57:07 +0000
From: Mel Gorman <mgorman@suse.de>
Subject: Re: [PATCH 7/7] mm: compaction: Introduce sync-light migration for
 use by compaction
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To: Nai Xia <nai.xia@gmail.com>
Cc: Shaohua Li <shaohua.li@intel.com>, Linux-MM <linux-mm@kvack.org>, Andrea Arcangeli <aarcange@redhat.com>, Minchan Kim <minchan.kim@gmail.com>, Jan Kara <jack@suse.cz>, Andy Isaacson <adi@hexapodia.org>, Johannes Weiner <jweiner@redhat.com>, Rik van Riel <riel@redhat.com>, LKML <linux-kernel@vger.kernel.org>

On Wed, Nov 23, 2011 at 11:23:19PM +0800, Nai Xia wrote:
> > <SNIP>
> > This would be functionally equivalent and satisfy THP users
> > but I do not see it as being easier to understand or easier
> > to maintain than updating the API. If someone in the future
> > wanted to use migration without significant stalls without
> > being PF_MEMALLOC, they would need to update the API like this.
> > There are no users like this today but automatic NUMA migration
> > might want to leverage something like MIGRATE_SYNC_LIGHT
> > (http://comments.gmane.org/gmane.linux.kernel.mm/70239)
> 
> I see.
> So could I say that might be the time and users for my suggestion of
> page uptodate check to fit into?
> 

Yes, at that point checking for PageUptodate may be necessary depending
on their requirements.

-- 
Mel Gorman
SUSE Labs

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