mm: compaction: make isolate_lru_page() filter-aware
authorMinchan Kim <minchan.kim@gmail.com>
Tue, 1 Nov 2011 00:06:51 +0000 (17:06 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 1 Nov 2011 00:30:44 +0000 (17:30 -0700)
commit39deaf8585152f1a35c1676d3d7dc6ae0fb65967
treea7509ea61c2f1028ed7ef961aa1abd16d50905f9
parent4356f21d09283dc6d39a6f7287a65ddab61e2808
mm: compaction: make isolate_lru_page() filter-aware

In async mode, compaction doesn't migrate dirty or writeback pages.  So,
it's meaningless to pick the page and re-add it to lru list.

Of course, when we isolate the page in compaction, the page might be dirty
or writeback but when we try to migrate the page, the page would be not
dirty, writeback.  So it could be migrated.  But it's very unlikely as
isolate and migration cycle is much faster than writeout.

So, this patch helps cpu overhead and prevent unnecessary LRU churning.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/mmzone.h
mm/compaction.c
mm/vmscan.c