Message-ID: <53DA62FB.7000108@redhat.com>
Date: Thu, 31 Jul 2014 11:38:35 -0400
From: Rik van Riel <riel@redhat.com>
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To: Jerome Marchand <jmarchan@redhat.com>, linux-mm@kvack.org
CC: linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>, Mel Gorman <mgorman@suse.de>,
        Michal Hocko <mhocko@suse.cz>
Subject: Re: [PATCH 2/2] memcg, vmscan: Fix forced scan of anonymous pages
References: <1406807385-5168-1-git-send-email-jmarchan@redhat.com> <1406807385-5168-3-git-send-email-jmarchan@redhat.com>
In-Reply-To: <1406807385-5168-3-git-send-email-jmarchan@redhat.com>
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On 07/31/2014 07:49 AM, Jerome Marchand wrote:
> When memory cgoups are enabled, the code that decides to force to
> scan anonymous pages in get_scan_count() compares global values
> (free, high_watermark) to a value that is restricted to a memory
> cgroup (file). It make the code over-eager to force anon scan.
> 
> For instance, it will force anon scan when scanning a memcg that
> is mainly populated by anonymous page, even when there is plenty of
> file pages to get rid of in others memcgs, even when swappiness ==
> 0. It breaks user's expectation about swappiness and hurts
> performance.
> 
> This patch make sure that forced anon scan only happens when there
> not enough file pages for the all zone, not just in one random
> memcg.
> 
> Signed-off-by: Jerome Marchand <jmarchan@redhat.com>

That fix is a lot smaller than I thought it would be. Nice.

Reviewed-by: Rik van Riel <riel@redhat.com>

- -- 
All rights reversed
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