Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932961Ab1EXOqi (ORCPT ); Tue, 24 May 2011 10:46:38 -0400 Received: from lon1-post-2.mail.demon.net ([195.173.77.149]:62874 "EHLO lon1-post-2.mail.demon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932085Ab1EXOqh (ORCPT ); Tue, 24 May 2011 10:46:37 -0400 X-Greylist: delayed 3395 seconds by postgrey-1.27 at vger.kernel.org; Tue, 24 May 2011 10:46:37 EDT Subject: [PATCH] x86: reorder mm_context_t to remove x86_64 alignment padding & so shrink mm_struct From: Richard Kennedy To: Ingo Molnar , Thomas Gleixner Cc: lkml , the arch/x86 maintainers , wilsons@start.ca Content-Type: text/plain; charset="UTF-8" Date: Tue, 24 May 2011 14:49:59 +0100 Message-ID: <1306244999.1999.5.camel@castor.rsk> Mime-Version: 1.0 X-Mailer: Evolution 2.32.2 (2.32.2-1.fc14) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1699 Lines: 67 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 --- patch against v2.6.39 compiled & tested on x86_64. regards Richard 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/