From: Richard Kennedy Date: Tue, 24 May 2011 13:49:59 +0000 (+0100) Subject: x86: Reorder mm_context_t to remove x86_64 alignment padding and thus shrink mm_struct X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=af6a25f0e1ec0265c267e6ee4513925eaba6d0ed;p=deliverable%2Flinux.git 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 Cc: wilsons@start.ca Cc: Linus Torvalds Cc: Andrew Morton Cc: Pekka Enberg Link: http://lkml.kernel.org/r/1306244999.1999.5.camel@castor.rsk Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h index aeff3e89b222..5f55e6962769 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