From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 2F07B6B01F0 for ; Sat, 28 Aug 2010 10:11:20 -0400 (EDT) Subject: [PATCH] mm: remove alignment padding from anon_vma on (some) 64 bit builds From: Richard Kennedy Content-Type: text/plain; charset="UTF-8" Date: Sat, 28 Aug 2010 15:09:46 +0100 Message-ID: <1283004586.1912.10.camel@castor.rsk> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: linux-mm , lkml , Rik van Riel List-ID: Reorder structure anon_vma to remove alignment padding on 64 builds when (CONFIG_KSM || CONFIG_MIGRATION). This will shrink the size of the anon_vma structure from 40 to 32 bytes & allow more objects per slab in its kmem_cache. Under slub the objects in the anon_vma kmem_cache will then be 40 bytes with 102 objects per slab. (On v2.6.36 without this patch,the size is 48 bytes and 85 objects/slab.) compiled & tested on x86_64 using SLUB Signed-off-by: Richard Kennedy --- patch against v2.6.36-rc2 compiled & tested on x86_64 AMD X2 regards Richard diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 31b2fd7..5c98df6 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -25,8 +25,8 @@ * pointing to this anon_vma once its vma list is empty. */ struct anon_vma { - spinlock_t lock; /* Serialize access to vma list */ struct anon_vma *root; /* Root of this anon_vma tree */ + spinlock_t lock; /* Serialize access to vma list */ #if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION) /* -- 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