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authorChristoph Lameter <clameter@sgi.com>2007-07-17 04:03:23 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-17 10:23:01 -0700
commitd07dbea46405b37d59495eb4de9d1056dcfb7c6d (patch)
tree221376c8c5509a88f8942246180685d5c01baf46 /mm/slab.c
parent6cb8f91320d3e720351c21741da795fed580b21b (diff)
downloadlinux-linaro-d07dbea46405b37d59495eb4de9d1056dcfb7c6d.tar.gz
Slab allocators: support __GFP_ZERO in all allocators
A kernel convention for many allocators is that if __GFP_ZERO is passed to an allocator then the allocated memory should be zeroed. This is currently not supported by the slab allocators. The inconsistency makes it difficult to implement in derived allocators such as in the uncached allocator and the pool allocators. In addition the support zeroed allocations in the slab allocators does not have a consistent API. There are no zeroing allocator functions for NUMA node placement (kmalloc_node, kmem_cache_alloc_node). The zeroing allocations are only provided for default allocs (kzalloc, kmem_cache_zalloc_node). __GFP_ZERO will make zeroing universally available and does not require any addititional functions. So add the necessary logic to all slab allocators to support __GFP_ZERO. The code is added to the hot path. The gfp flags are on the stack and so the cacheline is readily available for checking if we want a zeroed object. Zeroing while allocating is now a frequent operation and we seem to be gradually approaching a 1-1 parity between zeroing and not zeroing allocs. The current tree has 3476 uses of kmalloc vs 2731 uses of kzalloc. Signed-off-by: Christoph Lameter <clameter@sgi.com> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> 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.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/mm/slab.c b/mm/slab.c
index d2cd304fd8a..1a88fded7f1 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2746,7 +2746,7 @@ static int cache_grow(struct kmem_cache *cachep,
* Be lazy and only check for valid flags here, keeping it out of the
* critical path in kmem_cache_alloc().
*/
- BUG_ON(flags & ~(GFP_DMA | GFP_LEVEL_MASK));
+ BUG_ON(flags & ~(GFP_DMA | __GFP_ZERO | GFP_LEVEL_MASK));
local_flags = (flags & GFP_LEVEL_MASK);
/* Take the l3 list lock to change the colour_next on this node */
@@ -3392,6 +3392,9 @@ __cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
local_irq_restore(save_flags);
ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller);
+ if (unlikely((flags & __GFP_ZERO) && ptr))
+ memset(ptr, 0, obj_size(cachep));
+
return ptr;
}
@@ -3443,6 +3446,9 @@ __cache_alloc(struct kmem_cache *cachep, gfp_t flags, void *caller)
objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller);
prefetchw(objp);
+ if (unlikely((flags & __GFP_ZERO) && objp))
+ memset(objp, 0, obj_size(cachep));
+
return objp;
}