Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965188Ab3DJS0r (ORCPT ); Wed, 10 Apr 2013 14:26:47 -0400 Received: from g1t0027.austin.hp.com ([15.216.28.34]:37475 "EHLO g1t0027.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936652Ab3DJS0p (ORCPT ); Wed, 10 Apr 2013 14:26:45 -0400 From: Waiman Long Cc: Waiman Long , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, "Chandramouleeswaran, Aswin" , "Norton, Scott J" Subject: [PATCH RFC 2/2] SELinux: Increase ebitmap_node size for 64-bit configuration Date: Wed, 10 Apr 2013 14:26:23 -0400 Message-Id: <1365618383-29340-2-git-send-email-Waiman.Long@hp.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1365618383-29340-1-git-send-email-Waiman.Long@hp.com> References: <1365618383-29340-1-git-send-email-Waiman.Long@hp.com> To: Stephen Smalley , James Morris , Eric Paris Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1769 Lines: 47 Currently, the ebitmap_node structure has a fixed size of 32 bytes. On a 32-bit system, the overhead is 8 bytes, leaving 24 bytes for being used as bitmaps. The overhead ratio is 1/4. On a 64-bit system, the overhead is 16 bytes. Therefore, only 16 bytes are left for bitmap purpose and the overhead ratio is 1/2. With a 3.8.2 kernel, a boot-up operation will cause the ebitmap_get_bit() function to be called about 9 million times. The average number of ebitmap_node traversal is about 3.7. This patch increases the size of the ebitmap_node structure to 64 bytes for 64-bit system to keep the overhead ratio at 1/4. This may also improve performance a little bit by making node to node traversal less frequent (< 2) as more bits are available in each node. Signed-off-by: Waiman Long --- security/selinux/ss/ebitmap.h | 8 +++++++- 1 files changed, 7 insertions(+), 1 deletions(-) diff --git a/security/selinux/ss/ebitmap.h b/security/selinux/ss/ebitmap.h index 922f8af..653a5b9 100644 --- a/security/selinux/ss/ebitmap.h +++ b/security/selinux/ss/ebitmap.h @@ -16,7 +16,13 @@ #include -#define EBITMAP_UNIT_NUMS ((32 - sizeof(void *) - sizeof(u32)) \ +#ifdef CONFIG_64BIT +#define EBITMAP_NODE_SIZE 64 +#else +#define EBITMAP_NODE_SIZE 32 +#endif + +#define EBITMAP_UNIT_NUMS ((EBITMAP_NODE_SIZE-sizeof(void *)-sizeof(u32))\ / sizeof(unsigned long)) #define EBITMAP_UNIT_SIZE BITS_PER_LONG #define EBITMAP_SIZE (EBITMAP_UNIT_NUMS * EBITMAP_UNIT_SIZE) -- 1.7.1 -- 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/