lkml.org 
[lkml]   [2012]   [May]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] mm: consider all swapped back pages in used-once logic
On 05/17/2012 05:13 AM, Michal Hocko wrote:
> [64574746 vmscan: detect mapped file pages used only once] made mapped pages
> have another round in inactive list because they might be just short
> lived and so we could consider them again next time. This heuristic
> helps to reduce pressure on the active list with a streaming IO
> worklods.
> This patch fixes a regression introduced by this commit for heavy shmem
> based workloads because unlike Anon pages, which are excluded from this
> heuristic because they are usually long lived, shmem pages are handled
> as a regular page cache.
> This doesn't work quite well, unfortunately, if the workload is mostly
> backed by shmem (in memory database sitting on 80% of memory) with a
> streaming IO in the background (backup - up to 20% of memory). Anon
> inactive list is full of (dirty) shmem pages when watermarks are
> hit. Shmem pages are kept in the inactive list (they are referenced)
> in the first round and it is hard to reclaim anything else so we reach
> lower scanning priorities very quickly which leads to an excessive swap
> out.
>
> Let's fix this by excluding all swap backed pages (they tend to be long
> lived wrt. the regular page cache anyway) from used-once heuristic and
> rather activate them if they are referenced.
>
> CC: Johannes Weiner<hannes@cmpxchg.org>
> CC: Andrew Morton<akpm@linux-foundation.org>
> CC: Mel Gorman<mel@csn.ul.ie>
> CC: Minchan Kim<minchan@kernel.org>
> CC: KAMEZAWA Hiroyuki<kamezawa.hiroyu@jp.fujitsu.com>
> CC: Rik van Riel<riel@redhat.com>
> CC: stable [2.6.34+]
> Signed-off-by: Michal Hocko<mhocko@suse.cz>

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

--
All rights reversed


\
 
 \ /
  Last update: 2012-05-17 15:41    [from the cache]
©2003-2011 Jasper Spaans