lkml.org 
[lkml]   [2011]   [May]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:x86/urgent] x86: Reorder mm_context_t to remove x86_64 alignment padding and thus shrink mm_struct
Commit-ID:  af6a25f0e1ec0265c267e6ee4513925eaba6d0ed
Gitweb: http://git.kernel.org/tip/af6a25f0e1ec0265c267e6ee4513925eaba6d0ed
Author: Richard Kennedy <richard@rsk.demon.co.uk>
AuthorDate: Tue, 24 May 2011 14:49:59 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 25 May 2011 16:16:41 +0200

x86: Reorder mm_context_t to remove x86_64 alignment padding and thus shrink mm_struct

Reorder mm_context_t to remove alignment padding on 64 bit
builds shrinking its size from 64 to 56 bytes.

This allows mm_struct to shrink from 840 to 832 bytes, so using
one fewer cache lines, and getting more objects per slab when
using slub.

slabinfo mm_struct reports
before :-

Sizes (bytes) Slabs
-----------------------------------
Object : 840 Total : 7
SlabObj: 896 Full : 1
SlabSiz: 16384 Partial: 4
Loss : 56 CpuSlab: 2
Align : 64 Objects: 18

after :-

Sizes (bytes) Slabs
----------------------------------
Object : 832 Total : 7
SlabObj: 832 Full : 1
SlabSiz: 16384 Partial: 4
Loss : 0 CpuSlab: 2
Align : 64 Objects: 19

Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Cc: wilsons@start.ca
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Link: http://lkml.kernel.org/r/1306244999.1999.5.camel@castor.rsk
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/include/asm/mmu.h | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h
index aeff3e8..5f55e69 100644
--- a/arch/x86/include/asm/mmu.h
+++ b/arch/x86/include/asm/mmu.h
@@ -11,14 +11,14 @@
typedef struct {
void *ldt;
int size;
- struct mutex lock;
- void *vdso;

#ifdef CONFIG_X86_64
/* True if mm supports a task running in 32 bit compatibility mode. */
unsigned short ia32_compat;
#endif

+ struct mutex lock;
+ void *vdso;
} mm_context_t;

#ifdef CONFIG_SMP

\
 
 \ /
  Last update: 2011-05-25 23:37    [W:0.036 / U:1.060 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site