Messages in this thread | | | Date | Fri, 13 Dec 2013 10:45:49 -0500 | From | Rik van Riel <> | Subject | Re: [PATCH 1/7] mm: page_alloc: exclude unreclaimable allocations from zone fairness policy |
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On 12/13/2013 09:10 AM, Mel Gorman wrote: > From: Johannes Weiner <hannes@cmpxchg.org> > > Dave Hansen noted a regression in a microbenchmark that loops around > open() and close() on an 8-node NUMA machine and bisected it down to > 81c0a2bb515f ("mm: page_alloc: fair zone allocator policy"). That > change forces the slab allocations of the file descriptor to spread > out to all 8 nodes, causing remote references in the page allocator > and slab. > > The round-robin policy is only there to provide fairness among memory > allocations that are reclaimed involuntarily based on pressure in each > zone. It does not make sense to apply it to unreclaimable kernel > allocations that are freed manually, in this case instantly after the > allocation, and incur the remote reference costs twice for no reason. > > Only round-robin allocations that are usually freed through page > reclaim or slab shrinking. > > Cc: <stable@kernel.org> > Bisected-by: Dave Hansen <dave.hansen@intel.com> > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> > Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
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