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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2011-07-26 23:08:24 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2011-07-26 23:49:42 (GMT)
commit4508378b9523e22a2a0175d8bf64d932fb10a67d (patch)
treef7ebd57322edc18ff91ed7d71236fbbd5633c21c
parent1af8efe965676ab30d6c8a5b1fccc9229f339a3b (diff)
memcg: fix vmscan count in small memcgs
Commit 246e87a93934 ("memcg: fix get_scan_count() for small targets") fixes the memcg/kswapd behavior against small targets and prevent vmscan priority too high. But the implementation is too naive and adds another problem to small memcg. It always force scan to 32 pages of file/anon and doesn't handle swappiness and other rotate_info. It makes vmscan to scan anon LRU regardless of swappiness and make reclaim bad. This patch fixes it by adjusting scanning count with regard to swappiness at el. At a test "cat 1G file under 300M limit." (swappiness=20) before patch scanned_pages_by_limit 360919 scanned_anon_pages_by_limit 180469 scanned_file_pages_by_limit 180450 rotated_pages_by_limit 31 rotated_anon_pages_by_limit 25 rotated_file_pages_by_limit 6 freed_pages_by_limit 180458 freed_anon_pages_by_limit 19 freed_file_pages_by_limit 180439 elapsed_ns_by_limit 429758872 after patch scanned_pages_by_limit 180674 scanned_anon_pages_by_limit 24 scanned_file_pages_by_limit 180650 rotated_pages_by_limit 35 rotated_anon_pages_by_limit 24 rotated_file_pages_by_limit 11 freed_pages_by_limit 180634 freed_anon_pages_by_limit 0 freed_file_pages_by_limit 180634 elapsed_ns_by_limit 367119089 scanned_pages_by_system 0 the numbers of scanning anon are decreased(as expected), and elapsed time reduced. By this patch, small memcgs will work better. (*) Because the amount of file-cache is much bigger than anon, recalaim_stat's rotate-scan counter make scanning files more. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Michal Hocko <mhocko@suse.cz> Cc: Ying Han <yinghan@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/vmscan.c18
1 files changed, 12 insertions, 6 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 91cee9d..f87702a 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1795,6 +1795,7 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc,
enum lru_list l;
int noswap = 0;
int force_scan = 0;
+ unsigned long nr_force_scan[2];
anon = zone_nr_lru_pages(zone, sc, LRU_ACTIVE_ANON) +
@@ -1817,6 +1818,8 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc,
fraction[0] = 0;
fraction[1] = 1;
denominator = 1;
+ nr_force_scan[0] = 0;
+ nr_force_scan[1] = SWAP_CLUSTER_MAX;
goto out;
}
@@ -1828,6 +1831,8 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc,
fraction[0] = 1;
fraction[1] = 0;
denominator = 1;
+ nr_force_scan[0] = SWAP_CLUSTER_MAX;
+ nr_force_scan[1] = 0;
goto out;
}
}
@@ -1876,6 +1881,11 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc,
fraction[0] = ap;
fraction[1] = fp;
denominator = ap + fp + 1;
+ if (force_scan) {
+ unsigned long scan = SWAP_CLUSTER_MAX;
+ nr_force_scan[0] = div64_u64(scan * ap, denominator);
+ nr_force_scan[1] = div64_u64(scan * fp, denominator);
+ }
out:
for_each_evictable_lru(l) {
int file = is_file_lru(l);
@@ -1896,12 +1906,8 @@ out:
* memcg, priority drop can cause big latency. So, it's better
* to scan small amount. See may_noscan above.
*/
- if (!scan && force_scan) {
- if (file)
- scan = SWAP_CLUSTER_MAX;
- else if (!noswap)
- scan = SWAP_CLUSTER_MAX;
- }
+ if (!scan && force_scan)
+ scan = nr_force_scan[file];
nr[l] = scan;
}
}

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