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authorMel Gorman <mgorman@suse.de>2014-04-03 14:47:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-04-03 16:20:58 -0700
commitd26914d11751b23ca2e8747725f2cae10c2f2c1b (patch)
tree020b606fb9223e29292f54922a11111239e3a3f4 /mm/slab.c
parent91ca9186484809c57303b33778d841cc28f696ed (diff)
mm: optimize put_mems_allowed() usage
Since put_mems_allowed() is strictly optional, its a seqcount retry, we don't need to evaluate the function if the allocation was in fact successful, saving a smp_rmb some loads and comparisons on some relative fast-paths. Since the naming, get/put_mems_allowed() does suggest a mandatory pairing, rename the interface, as suggested by Mel, to resemble the seqcount interface. This gives us: read_mems_allowed_begin() and read_mems_allowed_retry(), where it is important to note that the return value of the latter call is inverted from its previous incarnation. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slab.c')
-rw-r--r--mm/slab.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/slab.c b/mm/slab.c
index b264214c77ea..9153c802e2fe 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3073,7 +3073,7 @@ static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
retry_cpuset:
- cpuset_mems_cookie = get_mems_allowed();
+ cpuset_mems_cookie = read_mems_allowed_begin();
zonelist = node_zonelist(slab_node(), flags);
retry:
@@ -3131,7 +3131,7 @@ retry:
}
}
- if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !obj))
+ if (unlikely(!obj && read_mems_allowed_retry(cpuset_mems_cookie)))
goto retry_cpuset;
return obj;
}