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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/mempolicy.c
parent91ca9186484809c57303b33778d841cc28f696ed (diff)
downloadop-kernel-dev-d26914d11751b23ca2e8747725f2cae10c2f2c1b.zip
op-kernel-dev-d26914d11751b23ca2e8747725f2cae10c2f2c1b.tar.gz
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/mempolicy.c')
-rw-r--r--mm/mempolicy.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 4755c85..e3ab028 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1899,7 +1899,7 @@ int node_random(const nodemask_t *maskp)
* If the effective policy is 'BIND, returns a pointer to the mempolicy's
* @nodemask for filtering the zonelist.
*
- * Must be protected by get_mems_allowed()
+ * Must be protected by read_mems_allowed_begin()
*/
struct zonelist *huge_zonelist(struct vm_area_struct *vma, unsigned long addr,
gfp_t gfp_flags, struct mempolicy **mpol,
@@ -2063,7 +2063,7 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
retry_cpuset:
pol = get_vma_policy(current, vma, addr);
- cpuset_mems_cookie = get_mems_allowed();
+ cpuset_mems_cookie = read_mems_allowed_begin();
if (unlikely(pol->mode == MPOL_INTERLEAVE)) {
unsigned nid;
@@ -2071,7 +2071,7 @@ retry_cpuset:
nid = interleave_nid(pol, vma, addr, PAGE_SHIFT + order);
mpol_cond_put(pol);
page = alloc_page_interleave(gfp, order, nid);
- if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
+ if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
goto retry_cpuset;
return page;
@@ -2081,7 +2081,7 @@ retry_cpuset:
policy_nodemask(gfp, pol));
if (unlikely(mpol_needs_cond_ref(pol)))
__mpol_put(pol);
- if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
+ if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
goto retry_cpuset;
return page;
}
@@ -2115,7 +2115,7 @@ struct page *alloc_pages_current(gfp_t gfp, unsigned order)
pol = &default_policy;
retry_cpuset:
- cpuset_mems_cookie = get_mems_allowed();
+ cpuset_mems_cookie = read_mems_allowed_begin();
/*
* No reference counting needed for current->mempolicy
@@ -2128,7 +2128,7 @@ retry_cpuset:
policy_zonelist(gfp, pol, numa_node_id()),
policy_nodemask(gfp, pol));
- if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
+ if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
goto retry_cpuset;
return page;
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