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Subject: Re: [PATCH 07/11] mm, compaction: Update compaction_result ordering
To: Michal Hocko <mhocko@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
References: <1459855533-4600-1-git-send-email-mhocko@kernel.org>
 <1459855533-4600-8-git-send-email-mhocko@kernel.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>
From: Vlastimil Babka <vbabka@suse.cz>
Message-ID: <570B95B6.6030509@suse.cz>
Date: Mon, 11 Apr 2016 14:16:54 +0200
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On 04/05/2016 01:25 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> compaction_result will be used as the primary feedback channel for
> compaction users. At the same time try_to_compact_pages (and potentially
> others) assume a certain ordering where a more specific feedback takes
> precendence. This gets a bit awkward when we have conflicting feedback
> from different zones. E.g one returing COMPACT_COMPLETE meaning the full
> zone has been scanned without any outcome while other returns with
> COMPACT_PARTIAL aka made some progress. The caller should get
> COMPACT_PARTIAL because that means that the compaction still can make
> some progress. The same applies for COMPACT_PARTIAL vs.
> COMPACT_PARTIAL_SKIPPED. Reorder PARTIAL to be the largest one so the
> larger the value is the more progress we have done.
>
> Signed-off-by: Michal Hocko <mhocko@suse.com>

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