From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx191.postini.com [74.125.245.191]) by kanga.kvack.org (Postfix) with SMTP id 1EB1A6B0068 for ; Wed, 24 Oct 2012 04:05:15 -0400 (EDT) Received: by mail-wg0-f45.google.com with SMTP id dq12so150420wgb.26 for ; Wed, 24 Oct 2012 01:05:13 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1350748093-7868-1-git-send-email-js1304@gmail.com> References: <1350748093-7868-1-git-send-email-js1304@gmail.com> Date: Wed, 24 Oct 2012 11:05:13 +0300 Message-ID: Subject: Re: [PATCH for-v3.7 1/2] slub: optimize poorly inlined kmalloc* functions From: Pekka Enberg Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Lameter On Sat, Oct 20, 2012 at 6:48 PM, Joonsoo Kim wrote: > 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 Looks reasonable to me. Christoph, any objections? > > 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 -- 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