From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx195.postini.com [74.125.245.195]) by kanga.kvack.org (Postfix) with SMTP id C55136B0062 for ; Sat, 20 Oct 2012 11:49:30 -0400 (EDT) Received: by mail-pa0-f41.google.com with SMTP id fa10so1115607pad.14 for ; Sat, 20 Oct 2012 08:49:30 -0700 (PDT) From: Joonsoo Kim Subject: [PATCH for-v3.7 1/2] slub: optimize poorly inlined kmalloc* functions Date: Sun, 21 Oct 2012 00:48:12 +0900 Message-Id: <1350748093-7868-1-git-send-email-js1304@gmail.com> In-Reply-To: References: Sender: owner-linux-mm@kvack.org List-ID: To: Pekka Enberg , Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Joonsoo Kim , Christoph Lameter kmalloc() and kmalloc_node() is always inlined into generic code. However, there is a mistake in implemention of the SLUB. In kmalloc() and kmalloc_node() of the SLUB, we try to compare kmalloc_caches[index] with NULL. As it cannot be known at compile time, this comparison is inserted into generic code invoking kmalloc*. This may decrease system performance, so we should fix it. Below is the result of "size vmlinux" text size is decreased roughly 20KB Before: text data bss dec hex filename 10044177 1443168 5722112 17209457 1069871 vmlinux After: text data bss dec hex filename 10022627 1443136 5722112 17187875 1064423 vmlinux Cc: Christoph Lameter Signed-off-by: Joonsoo Kim --- With Christoph's patchset(common kmalloc caches: '[15/15] Common Kmalloc cache determination') which is not merged into mainline yet, this issue will be fixed. As it takes some time, I send this patch for v3.7 This patch is based on v3.7-rc1 diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index df448ad..4c75f2b 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -271,9 +271,10 @@ static __always_inline void *kmalloc(size_t size, gfp_t flags) return kmalloc_large(size, flags); if (!(flags & SLUB_DMA)) { - struct kmem_cache *s = kmalloc_slab(size); + int index = kmalloc_index(size); + struct kmem_cache *s = kmalloc_caches[index]; - if (!s) + if (!index) return ZERO_SIZE_PTR; return kmem_cache_alloc_trace(s, flags, size); @@ -304,9 +305,10 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node) { if (__builtin_constant_p(size) && size <= SLUB_MAX_SIZE && !(flags & SLUB_DMA)) { - struct kmem_cache *s = kmalloc_slab(size); + int index = kmalloc_index(size); + struct kmem_cache *s = kmalloc_caches[index]; - if (!s) + if (!index) return ZERO_SIZE_PTR; return kmem_cache_alloc_node_trace(s, flags, node, size); -- 1.7.9.5 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org