Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1321061

[PATCH 5/3] mm, vmscan: make zone_reclaimable_pages more precise

Show all headers | View raw

From: Michal Hocko <mhocko@suse.com>

zone_reclaimable_pages is used in should_reclaim_retry which uses it to
calculate the target for the watermark check. This means that precise
numbers are important for the correct decision. zone_reclaimable_pages
uses zone_page_state which can contain stale data with per-cpu diffs
not synced yet (the last vmstat_update might have run 1s in the past).

Use zone_page_state_snapshot in zone_reclaimable_pages instead. None
of the current callers is in a hot path where getting the precise value
(which involves per-cpu iteration) would cause an unreasonable overhead.

Suggested-by: David Rientjes <rientjes@google.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/vmscan.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 489212252cd6..9145e3f89eab 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -196,21 +196,21 @@ unsigned long zone_reclaimable_pages(struct zone *zone)
 {
 	unsigned long nr;
 
-	nr = zone_page_state(zone, NR_ACTIVE_FILE) +
-	     zone_page_state(zone, NR_INACTIVE_FILE) +
-	     zone_page_state(zone, NR_ISOLATED_FILE);
+	nr = zone_page_state_snapshot(zone, NR_ACTIVE_FILE) +
+	     zone_page_state_snapshot(zone, NR_INACTIVE_FILE) +
+	     zone_page_state_snapshot(zone, NR_ISOLATED_FILE);
 
 	if (get_nr_swap_pages() > 0)
-		nr += zone_page_state(zone, NR_ACTIVE_ANON) +
-		      zone_page_state(zone, NR_INACTIVE_ANON) +
-		      zone_page_state(zone, NR_ISOLATED_ANON);
+		nr += zone_page_state_snapshot(zone, NR_ACTIVE_ANON) +
+		      zone_page_state_snapshot(zone, NR_INACTIVE_ANON) +
+		      zone_page_state_snapshot(zone, NR_ISOLATED_ANON);
 
 	return nr;
 }
 
 bool zone_reclaimable(struct zone *zone)
 {
-	return zone_page_state(zone, NR_PAGES_SCANNED) <
+	return zone_page_state_snapshot(zone, NR_PAGES_SCANNED) <
 		zone_reclaimable_pages(zone) * 6;
 }
 
-- 
2.7.0.rc3

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

[PATCH 5/3] mm, vmscan: make zone_reclaimable_pages more precise Michal Hocko <mhocko@kernel.org> - 2016-01-28 22:20 +0100
  Re: [PATCH 5/3] mm, vmscan: make zone_reclaimable_pages more  precise David Rientjes <rientjes@google.com> - 2016-01-29 00:30 +0100
  Re: [PATCH 5/3] mm, vmscan: make zone_reclaimable_pages more precise "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2016-01-29 04:50 +0100
  Re: [PATCH 5/3] mm, vmscan: make zone_reclaimable_pages more precise Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-01-29 11:40 +0100
    Re: [PATCH 5/3] mm, vmscan: make zone_reclaimable_pages more precise Michal Hocko <mhocko@kernel.org> - 2016-01-29 16:20 +0100
      Re: [PATCH 5/3] mm, vmscan: make zone_reclaimable_pages more precise Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-01-29 22:40 +0100

csiph-web