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Subject: Re: [PATCH 27/34] mm, vmscan: Have kswapd reclaim from all zones if
 reclaiming and buffer_heads_over_limit
References: <1467970510-21195-1-git-send-email-mgorman@techsingularity.net>
 <1467970510-21195-28-git-send-email-mgorman@techsingularity.net>
From: Vlastimil Babka <vbabka@suse.cz>
Message-ID: <6a33dd1a-ac19-ced1-a346-e83eea432780@suse.cz>
Date: Thu, 14 Jul 2016 14:54:27 +0200
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Sender: owner-linux-mm@kvack.org
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To: Mel Gorman <mgorman@techsingularity.net>, Andrew Morton <akpm@linux-foundation.org>, Linux-MM <linux-mm@kvack.org>
Cc: Rik van Riel <riel@surriel.com>, Johannes Weiner <hannes@cmpxchg.org>, Minchan Kim <minchan@kernel.org>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, LKML <linux-kernel@vger.kernel.org>

On 07/08/2016 11:35 AM, Mel Gorman wrote:
> The buffer_heads_over_limit limit in kswapd is inconsistent with direct
> reclaim behaviour. It may force an an attempt to reclaim from all zones and
> then not reclaim at all because higher zones were balanced than required
> by the original request.
>
> This patch will causes kswapd to consider reclaiming from all zones if
> buffer_heads_over_limit.  However, if there are eligible zones for the
> allocation request that woke kswapd then no reclaim will occur even if
> buffer_heads_over_limit. This avoids kswapd over-reclaiming just because
> buffer_heads_over_limit.
>
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>

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

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