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Date: Fri, 13 May 2011 10:49:58 +0100
From: Mel Gorman <mgorman@suse.de>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph Lameter <cl@linux.com>, Pekka Enberg <penberg@kernel.org>,
        James Bottomley <James.Bottomley@hansenpartnership.com>,
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Subject: Re: [PATCH 3/3] mm: slub: Default slub_max_order to 0
Message-ID: <20110513094958.GA3569@suse.de>
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On Thu, May 12, 2011 at 08:00:18PM +0200, Andrea Arcangeli wrote:
> <SNIP>
>
> BTW, it comes to mind in patch 2, SLUB should clear __GFP_REPEAT too
> (not only __GFP_NOFAIL). Clearing __GFP_WAIT may be worth it or not
> with COMPACTION=y, definitely good idea to clear __GFP_WAIT unless
> lumpy is restricted to __GFP_REPEAT|__GFP_NOFAIL.

This is in V2 (unreleased, testing in progress and was running
overnight). I noticed that clearing __GFP_REPEAT is required for
reclaim/compaction if direct reclaimers from SLUB are to return false in
should_continue_reclaim() and bail out from high-order allocation
properly. As it is, there is a possibility for slub high-order direct
reclaimers to loop in reclaim/compaction for a long time. This is
only important when CONFIG_COMPACTION=y.

-- 
Mel Gorman
SUSE Labs
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