From: Christoph Lameter <cl@linux-foundation.org>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: linux-mm@kvack.org, jamal <hadi@cyberus.ca>, netdev@vger.kernel.org
Subject: slub numa: Fix rare allocation from unexpected node
Date: Mon, 26 Jul 2010 10:41:14 -0500 (CDT) [thread overview]
Message-ID: <alpine.DEB.2.00.1007261040430.5438@router.home> (raw)
Subject: slub numa: Fix rare allocation from unexpected node
The network developers have seen sporadic allocations resulting in objects
coming from unexpected NUMA nodes despite asking for objects from a
specific node.
This is due to get_partial() calling get_any_partial() if partial
slabs are exhausted for a node even if a node was specified and therefore
one would expect allocations only from the specified node.
get_any_partial() sporadically may return a slab from a foreign
node to gradually reduce the size of partial lists on remote nodes
and thereby reduce total memory use for a slab cache.
The behavior is controlled by the remote_defrag_ratio of each cache.
Strictly speaking this is permitted behavior since __GFP_THISNODE was
not specified for the allocation but it is certain surprising.
This patch makes sure that the remote defrag behavior only occurs
if no node was specified.
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
---
mm/slub.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c 2010-07-23 09:24:11.000000000 -0500
+++ linux-2.6/mm/slub.c 2010-07-23 09:25:15.000000000 -0500
@@ -1390,7 +1390,7 @@ static struct page *get_partial(struct k
int searchnode = (node == -1) ? numa_node_id() : node;
page = get_partial_node(get_node(s, searchnode));
- if (page || (flags & __GFP_THISNODE))
+ if (page || node != -1)
return page;
return get_any_partial(s, flags);
--
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next reply other threads:[~2010-07-26 15:41 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-26 15:41 Christoph Lameter [this message]
2010-07-29 10:00 ` Pekka Enberg
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