55 lines
1.9 KiB
Diff
55 lines
1.9 KiB
Diff
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From 6b7025ea927d290a59d2772828435c1893f0267f Mon Sep 17 00:00:00 2001
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From: Rik van Riel <riel@redhat.com>
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Date: Fri, 7 Oct 2011 16:17:22 +0100
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Subject: [PATCH 1/2] mm: vmscan: Limit direct reclaim for higher order
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allocations
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When suffering from memory fragmentation due to unfreeable pages,
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THP page faults will repeatedly try to compact memory. Due to the
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unfreeable pages, compaction fails.
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Needless to say, at that point page reclaim also fails to create
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free contiguous 2MB areas. However, that doesn't stop the current
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code from trying, over and over again, and freeing a minimum of 4MB
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(2UL << sc->order pages) at every single invocation.
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This resulted in my 12GB system having 2-3GB free memory, a
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corresponding amount of used swap and very sluggish response times.
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This can be avoided by having the direct reclaim code not reclaim from
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zones that already have plenty of free memory available for compaction.
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If compaction still fails due to unmovable memory, doing additional
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reclaim will only hurt the system, not help.
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Signed-off-by: Rik van Riel <riel@redhat.com>
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Signed-off-by: Mel Gorman <mgorman@suse.de>
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---
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mm/vmscan.c | 10 ++++++++++
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1 files changed, 10 insertions(+), 0 deletions(-)
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diff --git a/mm/vmscan.c b/mm/vmscan.c
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index 6072d74..8c03534 100644
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--- a/mm/vmscan.c
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+++ b/mm/vmscan.c
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@@ -2022,6 +2022,16 @@ static void shrink_zones(int priority, struct zonelist *zonelist,
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continue;
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if (zone->all_unreclaimable && priority != DEF_PRIORITY)
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continue; /* Let kswapd poll it */
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+ if (COMPACTION_BUILD) {
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+ /*
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+ * If we already have plenty of memory free
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+ * for compaction, don't free any more.
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+ */
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+ if (sc->order > PAGE_ALLOC_COSTLY_ORDER &&
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+ (compaction_suitable(zone, sc->order) ||
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+ compaction_deferred(zone)))
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+ continue;
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+ }
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/*
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* This steals pages from memory cgroups over softlimit
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* and returns the number of reclaimed pages and
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--
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1.7.6.4
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