From: Mel Gorman <mgorman@suse.de>
To: Stable <stable@vger.kernel.org>
Cc: "Linux-MM <linux-mm"@kvack.org,
LKML <linux-kernel@vger.kernel.org>, Mel Gorman <mgorman@suse.de>
Subject: [PATCH 05/34] vmscan: clear ZONE_CONGESTED for zone with good watermark
Date: Thu, 19 Jul 2012 15:36:15 +0100 [thread overview]
Message-ID: <1342708604-26540-6-git-send-email-mgorman@suse.de> (raw)
In-Reply-To: <1342708604-26540-1-git-send-email-mgorman@suse.de>
From: Shaohua Li <shaohua.li@intel.com>
commit 439423f6894aa0dec22187526827456f5004baed upstream.
Stable note: Not tracked in Bugzilla. kswapd is responsible for clearing
ZONE_CONGESTED after it balances a zone and this patch fixes a bug
where that was failing to happen. Without this patch, processes
can stall in wait_iff_congested unnecessarily. For users, this can
look like an interactivity stall but some workloads would see it
as sudden drop in throughput.
ZONE_CONGESTED is only cleared in kswapd, but pages can be freed in any
task. It's possible ZONE_CONGESTED isn't cleared in some cases:
1. the zone is already balanced just entering balance_pgdat() for
order-0 because concurrent tasks free memory. In this case, later
check will skip the zone as it's balanced so the flag isn't cleared.
2. high order balance fallbacks to order-0. quote from Mel: At the
end of balance_pgdat(), kswapd uses the following logic;
If reclaiming at high order {
for each zone {
if all_unreclaimable
skip
if watermark is not met
order = 0
loop again
/* watermark is met */
clear congested
}
}
i.e. it clears ZONE_CONGESTED if it the zone is balanced. if not,
it restarts balancing at order-0. However, if the higher zones are
balanced for order-0, kswapd will miss clearing ZONE_CONGESTED as
that only happens after a zone is shrunk. This can mean that
wait_iff_congested() stalls unnecessarily.
This patch makes kswapd clear ZONE_CONGESTED during its initial
highmem->dma scan for zones that are already balanced.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
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>
---
mm/vmscan.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index bdfdec3..72340b84 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2456,6 +2456,9 @@ loop_again:
high_wmark_pages(zone), 0, 0)) {
end_zone = i;
break;
+ } else {
+ /* If balanced, clear the congested flag */
+ zone_clear_flag(zone, ZONE_CONGESTED);
}
}
if (i < 0)
--
1.7.9.2
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next prev parent reply other threads:[~2012-07-19 14:36 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-19 14:36 [PATCH 00/34] Memory management performance backports for -stable Mel Gorman
2012-07-19 14:36 ` [PATCH 01/34] mm: vmstat: cache align vm_stat Mel Gorman
2012-07-19 14:36 ` [PATCH 02/34] mm: memory hotplug: Check if pages are correctly reserved on a per-section basis Mel Gorman
2012-07-19 14:36 ` [PATCH 03/34] mm: Reduce the amount of work done when updating min_free_kbytes Mel Gorman
2012-07-19 14:36 ` [PATCH 04/34] mm: vmscan: fix force-scanning small targets without swap Mel Gorman
2012-07-19 14:36 ` Mel Gorman [this message]
2012-07-19 14:36 ` [PATCH 06/34] vmscan: add shrink_slab tracepoints Mel Gorman
2012-07-19 14:36 ` [PATCH 07/34] vmscan: shrinker->nr updates race and go wrong Mel Gorman
2012-07-19 14:36 ` [PATCH 08/34] vmscan: reduce wind up shrinker->nr when shrinker can't do work Mel Gorman
2012-07-19 14:36 ` [PATCH 09/34] mm: limit direct reclaim for higher order allocations Mel Gorman
2012-07-19 14:36 ` [PATCH 10/34] mm: Abort reclaim/compaction if compaction can proceed Mel Gorman
2012-07-19 14:36 ` [PATCH 11/34] mm: compaction: trivial clean up in acct_isolated() Mel Gorman
2012-07-19 14:36 ` [PATCH 12/34] mm: change isolate mode from #define to bitwise type Mel Gorman
2012-07-19 14:36 ` [PATCH 13/34] mm: compaction: make isolate_lru_page() filter-aware Mel Gorman
2012-07-19 14:36 ` [PATCH 14/34] mm: zone_reclaim: " Mel Gorman
2012-07-19 14:36 ` [PATCH 15/34] mm: migration: clean up unmap_and_move() Mel Gorman
2012-07-19 14:36 ` [PATCH 16/34] mm: compaction: Allow compaction to isolate dirty pages Mel Gorman
2012-07-19 14:36 ` [PATCH 17/34] mm: compaction: Determine if dirty pages can be migrated without blocking within ->migratepage Mel Gorman
2012-07-19 14:36 ` [PATCH 18/34] mm: page allocator: Do not call direct reclaim for THP allocations while compaction is deferred Mel Gorman
2012-07-19 14:36 ` [PATCH 19/34] mm: compaction: make isolate_lru_page() filter-aware again Mel Gorman
2012-07-19 14:36 ` [PATCH 20/34] kswapd: avoid unnecessary rebalance after an unsuccessful balancing Mel Gorman
2012-07-19 14:36 ` [PATCH 21/34] kswapd: assign new_order and new_classzone_idx after wakeup in sleeping Mel Gorman
2012-07-22 19:25 ` Hugh Dickins
2012-07-23 9:37 ` Mel Gorman
2012-07-19 14:36 ` [PATCH 22/34] mm: compaction: Introduce sync-light migration for use by compaction Mel Gorman
2012-07-19 14:36 ` [PATCH 23/34] mm: vmscan: When reclaiming for compaction, ensure there are sufficient free pages available Mel Gorman
2012-07-19 14:36 ` [PATCH 24/34] mm: vmscan: Do not OOM if aborting reclaim to start compaction Mel Gorman
2012-07-19 14:36 ` [PATCH 25/34] mm: vmscan: Check if reclaim should really abort even if compaction_ready() is true for one zone Mel Gorman
2012-07-19 14:36 ` [PATCH 26/34] vmscan: promote shared file mapped pages Mel Gorman
2012-07-19 14:36 ` [PATCH 27/34] vmscan: activate executable pages after first usage Mel Gorman
2012-07-19 14:36 ` [PATCH 28/34] mm/vmscan.c: consider swap space when deciding whether to continue reclaim Mel Gorman
2012-07-19 14:36 ` [PATCH 29/34] mm: test PageSwapBacked in lumpy reclaim Mel Gorman
2012-07-19 14:36 ` [PATCH 30/34] mm: vmscan: Do not force kswapd to scan small targets Mel Gorman
2012-07-19 14:36 ` [PATCH 31/34] cpusets: avoid looping when storing to mems_allowed if one node remains set Mel Gorman
2012-07-19 14:36 ` [PATCH 32/34] cpusets: stall when updating mems_allowed for mempolicy or disjoint nodemask Mel Gorman
2012-07-19 14:36 ` [PATCH 33/34] cpuset: mm: Reduce large amounts of memory barrier related damage v3 Mel Gorman
2012-07-19 14:36 ` [PATCH 34/34] mm/hugetlb: fix warning in alloc_huge_page/dequeue_huge_page_vma Mel Gorman
2012-07-22 22:58 ` [PATCH 00/34] Memory management performance backports for -stable Ben Hutchings
2012-07-23 9:16 ` Mel Gorman
-- strict thread matches above, loose matches on Subject: below --
2012-07-23 13:38 [PATCH 00/34] Memory management performance backports for -stable V2 Mel Gorman
2012-07-23 13:38 ` [PATCH 05/34] vmscan: clear ZONE_CONGESTED for zone with good watermark Mel Gorman
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