The patch titled
Subject: memcg, vmscan: Fix forced scan of anonymous pages
has been added to the -mm tree. Its filename is
memcg-vmscan-fix-forced-scan-of-anonymous-pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/memcg-vmscan-fix-forced-scan-of-anonymous-pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/memcg-vmscan-fix-forced-scan-of-anonymous-pages.patch
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------------------------------------------------------
From: "Jerome Marchand" <jmarchan@xxxxxxxxxx>
Subject: memcg, vmscan: Fix forced scan of anonymous pages
When memory cgoups are enabled, the code that decides to force to scan
anonymous pages in get_scan_count() compares global values (free,
high_watermark) to a value that is restricted to a memory cgroup (file).
It make the code over-eager to force anon scan.
For instance, it will force anon scan when scanning a memcg that is mainly
populated by anonymous page, even when there is plenty of file pages to
get rid of in others memcgs, even when swappiness == 0. It breaks user's
expectation about swappiness and hurts performance.
This patch makes sure that forced anon scan only happens when there not
enough file pages for the all zone, not just in one random memcg.
Signed-off-by: Jerome Marchand <jmarchan@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff -puN mm/vmscan.c~memcg-vmscan-fix-forced-scan-of-anonymous-pages mm/vmscan.c
--- a/mm/vmscan.c~memcg-vmscan-fix-forced-scan-of-anonymous-pages
+++ a/mm/vmscan.c
@@ -1950,8 +1950,11 @@ static void get_scan_count(struct lruvec
*/
if (global_reclaim(sc)) {
unsigned long free = zone_page_state(zone, NR_FREE_PAGES);
+ unsigned long zonefile =
+ zone_page_state(zone, NR_LRU_BASE + LRU_ACTIVE_FILE) +
+ zone_page_state(zone, NR_LRU_BASE + LRU_INACTIVE_FILE);
- if (unlikely(file + free <= high_wmark_pages(zone))) {
+ if (unlikely(zonefile + free <= high_wmark_pages(zone))) {
scan_balance = SCAN_ANON;
goto out;
}
_
Patches currently in -mm which might be from jmarchan@xxxxxxxxxx are
mm-make-copy_pte_range-static-again.patch
mm-vmscan-fix-an-outdated-comment-still-mentioning-get_scan_ratio.patch
memcg-vmscan-fix-forced-scan-of-anonymous-pages.patch
zram-use-size_t-instead-of-u16.patch
zram-remove-global-tb_lock-with-fine-grain-lock.patch
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