Messages in this thread Patch in this message | | | Date | Wed, 25 May 2011 21:34:26 GMT | From | tip-bot for Richard Kennedy <> | Subject | [tip:x86/urgent] x86: Reorder mm_context_t to remove x86_64 alignment padding and thus shrink mm_struct |
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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
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