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authorDavid Rientjes <rientjes@google.com>2014-04-07 15:37:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-04-07 16:35:54 -0700
commitf0432d159601f96839f514f286eaa5b75c4112dc (patch)
tree654f94de69e9b7465480172b09e6838f08e81989 /mm/slab.c
parent2a389610a7331d22344698f23ef2e8c55b2cde7b (diff)
downloadop-kernel-dev-f0432d159601f96839f514f286eaa5b75c4112dc.zip
op-kernel-dev-f0432d159601f96839f514f286eaa5b75c4112dc.tar.gz
mm, mempolicy: remove per-process flag
PF_MEMPOLICY is an unnecessary optimization for CONFIG_SLAB users. There's no significant performance degradation to checking current->mempolicy rather than current->flags & PF_MEMPOLICY in the allocation path, especially since this is considered unlikely(). Running TCP_RR with netperf-2.4.5 through localhost on 16 cpu machine with 64GB of memory and without a mempolicy: threads before after 16 1249409 1244487 32 1281786 1246783 48 1239175 1239138 64 1244642 1241841 80 1244346 1248918 96 1266436 1254316 112 1307398 1312135 128 1327607 1326502 Per-process flags are a scarce resource so we should free them up whenever possible and make them available. We'll be using it shortly for memcg oom reserves. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jianguo Wu <wujianguo@huawei.com> Cc: Tim Hockin <thockin@google.com> Cc: Christoph Lameter <cl@linux.com> 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 4b17f4c..3db4cb0 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3027,7 +3027,7 @@ out:
#ifdef CONFIG_NUMA
/*
- * Try allocating on another node if PF_SPREAD_SLAB|PF_MEMPOLICY.
+ * Try allocating on another node if PF_SPREAD_SLAB is a mempolicy is set.
*
* If we are in_interrupt, then process context, including cpusets and
* mempolicy, may not apply and should not be used for allocation policy.
@@ -3259,7 +3259,7 @@ __do_cache_alloc(struct kmem_cache *cache, gfp_t flags)
{
void *objp;
- if (unlikely(current->flags & (PF_SPREAD_SLAB | PF_MEMPOLICY))) {
+ if (current->mempolicy || unlikely(current->flags & PF_SPREAD_SLAB)) {
objp = alternate_node_alloc(cache, flags);
if (objp)
goto out;
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