From: Pekka Enberg <penberg@cs.helsinki.fi>
To: Christoph Lameter <cl@linux-foundation.org>
Cc: linux-mm@kvack.org, jamal <hadi@cyberus.ca>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: slub numa: Fix rare allocation from unexpected node
Date: Thu, 29 Jul 2010 13:00:23 +0300 [thread overview]
Message-ID: <4C515137.707@cs.helsinki.fi> (raw)
In-Reply-To: <alpine.DEB.2.00.1007261040430.5438@router.home>
Christoph Lameter wrote:
> 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);
Applied, thanks!
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prev parent reply other threads:[~2010-07-29 10:00 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-26 15:41 slub numa: Fix rare allocation from unexpected node Christoph Lameter
2010-07-29 10:00 ` Pekka Enberg [this message]
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