This is a note to let you know that I've just added the patch titled
mm: vmscan: do not apply pressure to slab if we are not applying pressure
to zone
to the 2.6.39-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-vmscan-do-not-apply-pressure-to-slab-if-we-are-not-applying-pressure-to-zone.patch
and it can be found in the queue-2.6.39 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <sta...@kernel.org> know about it.
>From mgor...@suse.de Mon Aug 1 11:50:25 2011
From: Mel Gorman <mgor...@suse.de>
Date: Mon, 11 Jul 2011 10:11:21 +0100
Subject: mm: vmscan: do not apply pressure to slab if we are not applying
pressure to zone
To: sta...@kernel.org
Cc: mgor...@suse.de
Message-ID: <1310375483-31999-3-git-send-email-mgor...@suse.de>
From: Mel Gorman <mgor...@suse.de>
commit d7868dae893c83c50c7824bc2bc75f93d114669f upstream
During allocator-intensive workloads, kswapd will be woken frequently
causing free memory to oscillate between the high and min watermark. This
is expected behaviour.
When kswapd applies pressure to zones during node balancing, it checks if
the zone is above a high+balance_gap threshold. If it is, it does not
apply pressure but it unconditionally shrinks slab on a global basis which
is excessive. In the event kswapd is being kept awake due to a high small
unreclaimable zone, it skips zone shrinking but still calls shrink_slab().
Once pressure has been applied, the check for zone being unreclaimable is
being made before the check is made if all_unreclaimable should be set.
This miss of unreclaimable can cause has_under_min_watermark_zone to be
set due to an unreclaimable zone preventing kswapd backing off on
congestion_wait().
Signed-off-by: Mel Gorman <mgor...@suse.de>
Reported-by: Pádraig Brady <p...@draigbrady.com>
Tested-by: Pádraig Brady <p...@draigbrady.com>
Tested-by: Andrew Lutomirski <l...@mit.edu>
Acked-by: Rik van Riel <r...@redhat.com>
Reviewed-by: Minchan Kim <minchan....@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com>
Cc: Johannes Weiner <han...@cmpxchg.org>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@suse.de>
---
mm/vmscan.c | 25 ++++++++++++++-----------
1 file changed, 14 insertions(+), 11 deletions(-)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2449,19 +2449,19 @@ loop_again:
KSWAPD_ZONE_BALANCE_GAP_RATIO);
if (!zone_watermark_ok_safe(zone, order,
high_wmark_pages(zone) + balance_gap,
- end_zone, 0))
+ end_zone, 0)) {
shrink_zone(priority, zone, &sc);
- reclaim_state->reclaimed_slab = 0;
- nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
- lru_pages);
- sc.nr_reclaimed += reclaim_state->reclaimed_slab;
- total_scanned += sc.nr_scanned;
- if (zone->all_unreclaimable)
- continue;
- if (nr_slab == 0 &&
- !zone_reclaimable(zone))
- zone->all_unreclaimable = 1;
+ reclaim_state->reclaimed_slab = 0;
+ nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
+ lru_pages);
+ sc.nr_reclaimed +=
reclaim_state->reclaimed_slab;
+ total_scanned += sc.nr_scanned;
+
+ if (nr_slab == 0 && !zone_reclaimable(zone))
+ zone->all_unreclaimable = 1;
+ }
+
/*
* If we've done a decent amount of scanning and
* the reclaim ratio is low, start doing writepage
@@ -2471,6 +2471,9 @@ loop_again:
total_scanned > sc.nr_reclaimed + sc.nr_reclaimed /
2)
sc.may_writepage = 1;
+ if (zone->all_unreclaimable)
+ continue;
+
if (!zone_watermark_ok_safe(zone, order,
high_wmark_pages(zone), end_zone, 0)) {
all_zones_ok = 0;
Patches currently in stable-queue which might be from mgor...@suse.de are
queue-2.6.39/mm-vmscan-evaluate-the-watermarks-against-the-correct.patch
queue-2.6.39/mm-compaction-ensure-that-the-compaction-free-scanner-does-not-move-to-the-next-zone.patch
queue-2.6.39/mm-vmscan-do-not-apply-pressure-to-slab-if-we-are-not-applying-pressure-to-zone.patch
queue-2.6.39/mm-vmscan-do-not-use-page_count-without-a-page-pin.patch
queue-2.6.39/vmscan-fix-a-livelock-in-kswapd.patch
queue-2.6.39/mm-vmscan-correct-check-for-kswapd-sleeping-in.patch
queue-2.6.39/mm-compaction-abort-compaction-if-too-many-pages-are-isolated-and-caller-is-asynchronous-v2.patch
queue-2.6.39/mm-vmscan-only-read-new_classzone_idx-from-pgdat-when-reclaiming-successfully.patch
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