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authorJerome Marchand <jmarchan@redhat.com>2014-08-06 16:08:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-06 18:01:22 -0700
commit2ab051e11bfa3cbb7b24177f3d6aaed10a0d743e (patch)
tree5262105b4933396587db86a36cbd28d5db37ceac
parent7c0db9e917f77e6de2a524b33b5436491850dc79 (diff)
downloadlinux-2ab051e11bfa3cbb7b24177f3d6aaed10a0d743e.tar.gz
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. [hannes@cmpxchg.org: cleanups] Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/vmscan.c20
1 files changed, 13 insertions, 7 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 88ab53c9949a..d2f65c856350 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1930,11 +1930,6 @@ static void get_scan_count(struct lruvec *lruvec, int swappiness,
goto out;
}
- anon = get_lru_size(lruvec, LRU_ACTIVE_ANON) +
- get_lru_size(lruvec, LRU_INACTIVE_ANON);
- file = get_lru_size(lruvec, LRU_ACTIVE_FILE) +
- get_lru_size(lruvec, LRU_INACTIVE_FILE);
-
/*
* Prevent the reclaimer from falling into the cache trap: as
* cache pages start out inactive, every cache fault will tip
@@ -1945,9 +1940,14 @@ static void get_scan_count(struct lruvec *lruvec, int swappiness,
* anon pages. Try to detect this based on file LRU size.
*/
if (global_reclaim(sc)) {
- unsigned long free = zone_page_state(zone, NR_FREE_PAGES);
+ unsigned long zonefile;
+ unsigned long zonefree;
+
+ zonefree = zone_page_state(zone, NR_FREE_PAGES);
+ zonefile = zone_page_state(zone, NR_ACTIVE_FILE) +
+ zone_page_state(zone, NR_INACTIVE_FILE);
- if (unlikely(file + free <= high_wmark_pages(zone))) {
+ if (unlikely(zonefile + zonefree <= high_wmark_pages(zone))) {
scan_balance = SCAN_ANON;
goto out;
}
@@ -1982,6 +1982,12 @@ static void get_scan_count(struct lruvec *lruvec, int swappiness,
*
* anon in [0], file in [1]
*/
+
+ anon = get_lru_size(lruvec, LRU_ACTIVE_ANON) +
+ get_lru_size(lruvec, LRU_INACTIVE_ANON);
+ file = get_lru_size(lruvec, LRU_ACTIVE_FILE) +
+ get_lru_size(lruvec, LRU_INACTIVE_FILE);
+
spin_lock_irq(&zone->lru_lock);
if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
reclaim_stat->recent_scanned[0] /= 2;