68 lines
2.6 KiB
Diff
68 lines
2.6 KiB
Diff
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From owner-linux-mm@kvack.org Wed May 11 11:35:30 2011
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From: Mel Gorman <mgorman@suse.de>
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To: Andrew Morton <akpm@linux-foundation.org>
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Subject: [PATCH 3/3] mm: slub: Default slub_max_order to 0
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Date: Wed, 11 May 2011 16:29:33 +0100
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Message-Id: <1305127773-10570-4-git-send-email-mgorman@suse.de>
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To avoid locking and per-cpu overhead, SLUB optimisically uses
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high-order allocations up to order-3 by default and falls back to
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lower allocations if they fail. While care is taken that the caller
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and kswapd take no unusual steps in response to this, there are
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further consequences like shrinkers who have to free more objects to
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release any memory. There is anecdotal evidence that significant time
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is being spent looping in shrinkers with insufficient progress being
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made (https://lkml.org/lkml/2011/4/28/361) and keeping kswapd awake.
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SLUB is now the default allocator and some bug reports have been
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pinned down to SLUB using high orders during operations like
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copying large amounts of data. SLUBs use of high-orders benefits
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applications that are sized to memory appropriately but this does not
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necessarily apply to large file servers or desktops. This patch
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causes SLUB to use order-0 pages like SLAB does by default.
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There is further evidence that this keeps kswapd's usage lower
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(https://lkml.org/lkml/2011/5/10/383).
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Signed-off-by: Mel Gorman <mgorman@suse.de>
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---
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Documentation/vm/slub.txt | 2 +-
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mm/slub.c | 2 +-
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2 files changed, 2 insertions(+), 2 deletions(-)
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diff --git a/Documentation/vm/slub.txt b/Documentation/vm/slub.txt
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index 07375e7..778e9fa 100644
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--- a/Documentation/vm/slub.txt
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+++ b/Documentation/vm/slub.txt
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@@ -117,7 +117,7 @@ can be influenced by kernel parameters:
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slub_min_objects=x (default 4)
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slub_min_order=x (default 0)
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-slub_max_order=x (default 1)
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+slub_max_order=x (default 0)
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slub_min_objects allows to specify how many objects must at least fit
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into one slab in order for the allocation order to be acceptable.
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diff --git a/mm/slub.c b/mm/slub.c
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index 1071723..23a4789 100644
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--- a/mm/slub.c
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+++ b/mm/slub.c
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@@ -2198,7 +2198,7 @@ EXPORT_SYMBOL(kmem_cache_free);
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* take the list_lock.
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*/
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static int slub_min_order;
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-static int slub_max_order = PAGE_ALLOC_COSTLY_ORDER;
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+static int slub_max_order;
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static int slub_min_objects;
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/*
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--
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1.7.3.4
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--
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