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Date: Fri, 12 Dec 2008 01:31:30 +0100 From: Nick Piggin <npiggin@...e.de> To: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Linux Memory Management List <linux-mm@...ck.org> Subject: [rfc][patch] mm: kfree_size Introduce kfree_size(). Some allocators can do a better job at kfree if the size of the freed object is known in advance. skb layer in the networking stack can use kfree intensively, and in that case, the size information should be hot in cache, so it should be a win to use kfree_size here. Allocators which don't care so much could just define kfree_size to kfree. Thoughts? Any other good candidate callers? --- include/linux/slqb_def.h | 15 +++++++++++++++ mm/slqb.c | 12 ++++++++++++ net/core/skbuff.c | 7 ++++++- 3 files changed, 33 insertions(+), 1 deletion(-) Index: linux-2.6/include/linux/slqb_def.h =================================================================== --- linux-2.6.orig/include/linux/slqb_def.h +++ linux-2.6/include/linux/slqb_def.h @@ -222,6 +222,21 @@ void *__kmalloc(size_t size, gfp_t flags #define KMALLOC_HEADER (ARCH_KMALLOC_MINALIGN < sizeof(void *) ? sizeof(void *) : ARCH_KMALLOC_MINALIGN) +void __kfree_size(const void *mem, size_t size); +static __always_inline void kfree_size(void *mem, size_t size) +{ + if (__builtin_constant_p(size)) { + struct kmem_cache *s; + + s = kmalloc_slab(size, 0); + if (unlikely(ZERO_OR_NULL_PTR(s))) + return; + + kmem_cache_free(s, mem); + } + __kfree_size(mem, size); +} + static __always_inline void *kmalloc(size_t size, gfp_t flags) { if (__builtin_constant_p(size)) { Index: linux-2.6/mm/slqb.c =================================================================== --- linux-2.6.orig/mm/slqb.c +++ linux-2.6/mm/slqb.c @@ -2118,6 +2118,18 @@ void *__kmalloc_node(size_t size, gfp_t EXPORT_SYMBOL(__kmalloc_node); #endif +void __kfree_size(const void *mem, size_t size) +{ + struct kmem_cache *s; + + s = get_slab(size, 0); + + if (unlikely(ZERO_OR_NULL_PTR(s))) + return; + + kmem_cache_free(s, mem); +} + size_t ksize(const void *object) { struct slqb_page *page; Index: linux-2.6/net/core/skbuff.c =================================================================== --- linux-2.6.orig/net/core/skbuff.c +++ linux-2.6/net/core/skbuff.c @@ -336,6 +336,11 @@ static void skb_release_data(struct sk_b if (!skb->cloned || !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : 1, &skb_shinfo(skb)->dataref)) { +#ifdef NET_SKBUFF_DATA_USES_OFFSET + int size = skb->end; +#else + int size = skb->end - skb->head; +#endif if (skb_shinfo(skb)->nr_frags) { int i; for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) @@ -345,7 +350,7 @@ static void skb_release_data(struct sk_b if (skb_shinfo(skb)->frag_list) skb_drop_fraglist(skb); - kfree(skb->head); + kfree_size(skb->head, size); } } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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