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Subject: Re: [PATCH] mm, vmscan: do not count freed pages as PGDEACTIVATE
References: <20170112211221.17636-1-mhocko@kernel.org>
From: Vlastimil Babka <vbabka@suse.cz>
Message-ID: <2ebf38a0-d8b3-c4bb-3351-b6053332a116@suse.cz>
Date: Fri, 13 Jan 2017 10:55:00 +0100
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Sender: owner-linux-mm@kvack.org
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To: Michal Hocko <mhocko@kernel.org>, Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>, Johannes Weiner <hannes@cmpxchg.org>, Mel Gorman <mgorman@suse.de>, linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>, Michal Hocko <mhocko@suse.com>

On 01/12/2017 10:12 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> PGDEACTIVATE represents the number of pages moved from the active list
> to the inactive list. At least this sounds like the original motivation
> of the counter. move_active_pages_to_lru, however, counts pages which
> got freed in the mean time as deactivated as well. This is a very rare
> event and counting them as deactivation in itself is not harmful but it
> makes the code more convoluted than necessary - we have to count both
> all pages and those which are freed which is a bit confusing.
>
> After this patch the PGDEACTIVATE should have a slightly more clear
> semantic and only count those pages which are moved from the active to
> the inactive list which is a plus.
>
> Suggested-by: Vlastimil Babka <vbabka@suse.cz>
> Signed-off-by: Michal Hocko <mhocko@suse.com>

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

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