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authorMel Gorman <mgorman@suse.de>2014-08-28 19:35:42 +0100
committerJiri Slaby <jslaby@suse.cz>2014-09-26 11:52:09 +0200
commit4a4ede23dd902513b3a17d3e61cef9baf650d33e (patch)
tree51a179f456b40d97cc89a35a8045c3428cc334f6 /include
parentb4fc580f75325271de2841891bb5816cea5ca101 (diff)
mm: move zone->pages_scanned into a vmstat counter
commit 0d5d823ab4e608ec7b52ac4410de4cb74bbe0edd upstream. zone->pages_scanned is a write-intensive cache line during page reclaim and it's also updated during page free. Move the counter into vmstat to take advantage of the per-cpu updates and do not update it in the free paths unless necessary. On a small UMA machine running tiobench the difference is marginal. On a 4-node machine the overhead is more noticable. Note that automatic NUMA balancing was disabled for this test as otherwise the system CPU overhead is unpredictable. 3.16.0-rc3 3.16.0-rc3 3.16.0-rc3 vanillarearrange-v5 vmstat-v5 User 746.94 759.78 774.56 System 65336.22 58350.98 32847.27 Elapsed 27553.52 27282.02 27415.04 Note that the overhead reduction will vary depending on where exactly pages are allocated and freed. Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'include')
-rw-r--r--include/linux/mmzone.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 9ff35dad8f21..1df12c6a80d8 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -143,6 +143,7 @@ enum zone_stat_item {
NR_SHMEM, /* shmem pages (included tmpfs/GEM pages) */
NR_DIRTIED, /* page dirtyings since bootup */
NR_WRITTEN, /* page writings since bootup */
+ NR_PAGES_SCANNED, /* pages scanned since last reclaim */
#ifdef CONFIG_NUMA
NUMA_HIT, /* allocated in intended node */
NUMA_MISS, /* allocated in non intended node */
@@ -478,7 +479,6 @@ struct zone {
/* Fields commonly accessed by the page reclaim scanner */
spinlock_t lru_lock;
- unsigned long pages_scanned; /* since last reclaim */
struct lruvec lruvec;
/*