* [PATCH] slab: Make allocations with GFP_ZERO slightly more efficient
@ 2013-09-11 0:02 Joe Perches
2013-09-11 14:17 ` Christoph Lameter
0 siblings, 1 reply; 2+ messages in thread
From: Joe Perches @ 2013-09-11 0:02 UTC (permalink / raw)
To: Christoph Lameter, Pekka Enberg, Matt Mackall; +Cc: linux-mm, LKML
Use the likely mechanism already around valid
pointer tests to better choose when to memset
to 0 allocations with __GFP_ZERO
Signed-off-by: Joe Perches <joe@perches.com>
---
mm/slab.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/mm/slab.c b/mm/slab.c
index 2580db0..94e7e54 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3392,11 +3392,11 @@ slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
kmemleak_alloc_recursive(ptr, cachep->object_size, 1, cachep->flags,
flags);
- if (likely(ptr))
+ if (likely(ptr)) {
kmemcheck_slab_alloc(cachep, flags, ptr, cachep->object_size);
-
- if (unlikely((flags & __GFP_ZERO) && ptr))
- memset(ptr, 0, cachep->object_size);
+ if (unlikely(flags & __GFP_ZERO))
+ memset(ptr, 0, cachep->object_size);
+ }
return ptr;
}
@@ -3457,11 +3457,11 @@ slab_alloc(struct kmem_cache *cachep, gfp_t flags, unsigned long caller)
flags);
prefetchw(objp);
- if (likely(objp))
+ if (likely(objp)) {
kmemcheck_slab_alloc(cachep, flags, objp, cachep->object_size);
-
- if (unlikely((flags & __GFP_ZERO) && objp))
- memset(objp, 0, cachep->object_size);
+ if (unlikely(flags & __GFP_ZERO))
+ memset(objp, 0, cachep->object_size);
+ }
return objp;
}
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^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] slab: Make allocations with GFP_ZERO slightly more efficient
2013-09-11 0:02 [PATCH] slab: Make allocations with GFP_ZERO slightly more efficient Joe Perches
@ 2013-09-11 14:17 ` Christoph Lameter
0 siblings, 0 replies; 2+ messages in thread
From: Christoph Lameter @ 2013-09-11 14:17 UTC (permalink / raw)
To: Joe Perches; +Cc: Pekka Enberg, Matt Mackall, linux-mm, LKML
On Tue, 10 Sep 2013, Joe Perches wrote:
> Use the likely mechanism already around valid
> pointer tests to better choose when to memset
> to 0 allocations with __GFP_ZERO
Ok but that is not that important since the first ptr check is only for
debuggin.
Acked-by: Christoph Lameter <cl@linux.com>
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