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authorKonstantin Khlebnikov <khlebnikov@openvz.org>2012-01-10 15:06:59 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-01-10 16:30:41 -0800
commit34dbc67a644f11ab3475d822d72e25409911e760 (patch)
tree56673160df54f71d71bcf91ac5328ec225c28c98 /mm/vmscan.c
parent1edf223485c42c99655dcd001db1e46ad5e5d2d7 (diff)
vmscan: promote shared file mapped pages
Commit 645747462435 ("vmscan: detect mapped file pages used only once") greatly decreases lifetime of single-used mapped file pages. Unfortunately it also decreases life time of all shared mapped file pages. Because after commit bf3f3bc5e7347 ("mm: don't mark_page_accessed in fault path") page-fault handler does not mark page active or even referenced. Thus page_check_references() activates file page only if it was used twice while it stays in inactive list, meanwhile it activates anon pages after first access. Inactive list can be small enough, this way reclaimer can accidentally throw away any widely used page if it wasn't used twice in short period. After this patch page_check_references() also activate file mapped page at first inactive list scan if this page is already used multiple times via several ptes. I found this while trying to fix degragation in rhel6 (~2.6.32) from rhel5 (~2.6.18). There a complete mess with >100 web/mail/spam/ftp containers, they share all their files but there a lot of anonymous pages: ~500mb shared file mapped memory and 15-20Gb non-shared anonymous memory. In this situation major-pagefaults are very costly, because all containers share the same page. In my load kernel created a disproportionate pressure on the file memory, compared with the anonymous, they equaled only if I raise swappiness up to 150 =) These patches actually wasn't helped a lot in my problem, but I saw noticable (10-20 times) reduce in count and average time of major-pagefault in file-mapped areas. Actually both patches are fixes for commit v2.6.33-5448-g6457474, because it was aimed at one scenario (singly used pages), but it breaks the logic in other scenarios (shared and/or executable pages) Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Acked-by: Pekka Enberg <penberg@kernel.org> Acked-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 11adc890ce3..753c1e6755f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -715,7 +715,7 @@ static enum page_references page_check_references(struct page *page,
*/
SetPageReferenced(page);
- if (referenced_page)
+ if (referenced_page || referenced_ptes > 1)
return PAGEREF_ACTIVATE;
return PAGEREF_KEEP;