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authorMel Gorman <mgorman@suse.de>2014-08-06 16:07:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-06 18:01:20 -0700
commit0d5d823ab4e608ec7b52ac4410de4cb74bbe0edd (patch)
tree7b9d8f7625e45c28ad626c7b5419e8e33c59788e /mm
parent3484b2de9499df23c4604a513b36f96326ae81ad (diff)
downloadlinux-0d5d823ab4e608ec7b52ac4410de4cb74bbe0edd.tar.gz
mm: move zone->pages_scanned into a vmstat counter
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>
Diffstat (limited to 'mm')
-rw-r--r--mm/page_alloc.c12
-rw-r--r--mm/vmscan.c7
-rw-r--r--mm/vmstat.c3
3 files changed, 15 insertions, 7 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b7381d11f021..daa016063793 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -680,9 +680,12 @@ static void free_pcppages_bulk(struct zone *zone, int count,
int migratetype = 0;
int batch_free = 0;
int to_free = count;
+ unsigned long nr_scanned;
spin_lock(&zone->lock);
- zone->pages_scanned = 0;
+ nr_scanned = zone_page_state(zone, NR_PAGES_SCANNED);
+ if (nr_scanned)
+ __mod_zone_page_state(zone, NR_PAGES_SCANNED, -nr_scanned);
while (to_free) {
struct page *page;
@@ -731,8 +734,11 @@ static void free_one_page(struct zone *zone,
unsigned int order,
int migratetype)
{
+ unsigned long nr_scanned;
spin_lock(&zone->lock);
- zone->pages_scanned = 0;
+ nr_scanned = zone_page_state(zone, NR_PAGES_SCANNED);
+ if (nr_scanned)
+ __mod_zone_page_state(zone, NR_PAGES_SCANNED, -nr_scanned);
__free_one_page(page, pfn, zone, order, migratetype);
if (unlikely(!is_migrate_isolate(migratetype)))
@@ -3248,7 +3254,7 @@ void show_free_areas(unsigned int filter)
K(zone_page_state(zone, NR_BOUNCE)),
K(zone_page_state(zone, NR_FREE_CMA_PAGES)),
K(zone_page_state(zone, NR_WRITEBACK_TEMP)),
- zone->pages_scanned,
+ K(zone_page_state(zone, NR_PAGES_SCANNED)),
(!zone_reclaimable(zone) ? "yes" : "no")
);
printk("lowmem_reserve[]:");
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5fec1ba9951f..9c8222b499b4 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -174,7 +174,8 @@ static unsigned long zone_reclaimable_pages(struct zone *zone)
bool zone_reclaimable(struct zone *zone)
{
- return zone->pages_scanned < zone_reclaimable_pages(zone) * 6;
+ return zone_page_state(zone, NR_PAGES_SCANNED) <
+ zone_reclaimable_pages(zone) * 6;
}
static unsigned long get_lru_size(struct lruvec *lruvec, enum lru_list lru)
@@ -1508,7 +1509,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
__mod_zone_page_state(zone, NR_ISOLATED_ANON + file, nr_taken);
if (global_reclaim(sc)) {
- zone->pages_scanned += nr_scanned;
+ __mod_zone_page_state(zone, NR_PAGES_SCANNED, nr_scanned);
if (current_is_kswapd())
__count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scanned);
else
@@ -1698,7 +1699,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold,
&nr_scanned, sc, isolate_mode, lru);
if (global_reclaim(sc))
- zone->pages_scanned += nr_scanned;
+ __mod_zone_page_state(zone, NR_PAGES_SCANNED, nr_scanned);
reclaim_stat->recent_scanned[file] += nr_taken;
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 8267f77d1875..e574e883fa70 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -763,6 +763,7 @@ const char * const vmstat_text[] = {
"nr_shmem",
"nr_dirtied",
"nr_written",
+ "nr_pages_scanned",
#ifdef CONFIG_NUMA
"numa_hit",
@@ -1067,7 +1068,7 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
min_wmark_pages(zone),
low_wmark_pages(zone),
high_wmark_pages(zone),
- zone->pages_scanned,
+ zone_page_state(zone, NR_PAGES_SCANNED),
zone->spanned_pages,
zone->present_pages,
zone->managed_pages);