linux-kernel - Re: [patch] mm, thp: restructure thp avoidance of light synchronous migration

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Message-ID: <20140725153859.GK10819@suse.de>
Date:	Fri, 25 Jul 2014 16:38:59 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [patch] mm, thp: restructure thp avoidance of light synchronous
 migration

On Thu, Jul 24, 2014 at 03:41:06PM -0700, David Rientjes wrote:
> __GFP_NO_KSWAPD, once the way to determine if an allocation was for thp or not, 
> has gained more users.  Their use is not necessarily wrong, they are trying to 
> do a memory allocation that can easily fail without disturbing kswapd, so the 
> bit has gained additional usecases.
> 
> This restructures the check to determine whether MIGRATE_SYNC_LIGHT should be 
> used for memory compaction in the page allocator.  Rather than testing solely 
> for __GFP_NO_KSWAPD, test for all bits that must be set for thp allocations.
> 
> This also moves the check to be done only after the page allocator is aborted 
> for deferred or contended memory compaction since setting migration_mode for 
> this case is pointless.
> 
> Signed-off-by: David Rientjes <rientjes@...gle.com>

Acked-by: Mel Gorman <mgorman@...e.de>

-- 
Mel Gorman
SUSE Labs
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