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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2010-10-26 14:21:46 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-10-26 16:52:08 -0700
commit2e30244a7cc1ff09013a1238d415b4076406388e (patch)
treef555a78df877bbbd300ba3ebce6e31b5609e965f /mm
parent4cbec4c8b9fda9ec784086fe7f74cd32a8adda95 (diff)
downloadvexpress-lsk-2e30244a7cc1ff09013a1238d415b4076406388e.tar.gz
vmscan,tmpfs: treat used once pages on tmpfs as used once
When a page has PG_referenced, shrink_page_list() discards it only if it is not dirty. This rule works fine if the backing filesystem is a regular one. PG_dirty is a good signal that the page was used recently because the flusher threads clean pages periodically. In addition, page writeback is costlier than simple page discard. However, when a page is on tmpfs this heuristic doesn't work because flusher threads don't write back tmpfs pages. Consequently tmpfs pages always rotate around the lru twice at least and adds unnecessary lru churn. Simple tmpfs streaming io shouldn't cause large anonymous page swap-out. Remove this unncessary reclaim bonus of tmpfs pages. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Reviewed-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/vmscan.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 30fd658bb28..b8a6fdc2131 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -651,7 +651,7 @@ static enum page_references page_check_references(struct page *page,
}
/* Reclaim if clean, defer dirty pages to writeback */
- if (referenced_page)
+ if (referenced_page && !PageSwapBacked(page))
return PAGEREF_RECLAIM_CLEAN;
return PAGEREF_RECLAIM;