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Subject: Re: [PATCH 08/14] mm, compaction: Abstract compaction feedback to
 helpers
References: <1461181647-8039-1-git-send-email-mhocko@kernel.org>
 <1461181647-8039-9-git-send-email-mhocko@kernel.org>
From: Vlastimil Babka <vbabka@suse.cz>
Message-ID: <5721CE20.6070801@suse.cz>
Date: Thu, 28 Apr 2016 10:47:28 +0200
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To: Michal Hocko <mhocko@kernel.org>, Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>, Johannes Weiner <hannes@cmpxchg.org>, Mel Gorman <mgorman@suse.de>, David Rientjes <rientjes@google.com>, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, Joonsoo Kim <js1304@gmail.com>, Hillf Danton <hillf.zj@alibaba-inc.com>, linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>, Michal Hocko <mhocko@suse.com>

On 04/20/2016 09:47 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> Compaction can provide a wild variation of feedback to the caller. Many
> of them are implementation specific and the caller of the compaction
> (especially the page allocator) shouldn't be bound to specifics of the
> current implementation.
>
> This patch abstracts the feedback into three basic types:
> 	- compaction_made_progress - compaction was active and made some
> 	  progress.
> 	- compaction_failed - compaction failed and further attempts to
> 	  invoke it would most probably fail and therefore it is not
> 	  worth retrying
> 	- compaction_withdrawn - compaction wasn't invoked for an
>            implementation specific reasons. In the current implementation
>            it means that the compaction was deferred, contended or the
>            page scanners met too early without any progress. Retrying is
>            still worthwhile.
>
> [vbabka@suse.cz: do not change thp back off behavior]
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

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