From patchwork Thu Sep  2 05:46:25 2010
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
X-Patchwork-Submitter: Miao Xie <miaox@cn.fujitsu.com>
X-Patchwork-Id: 148451
Received: from vger.kernel.org (vger.kernel.org [209.132.180.67])
	by demeter1.kernel.org (8.14.4/8.14.3) with ESMTP id o825oOom024761
	for <patchwork-linux-btrfs@patchwork.kernel.org>;
	Thu, 2 Sep 2010 05:51:16 GMT
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1753578Ab0IBFrJ (ORCPT
	<rfc822;patchwork-linux-btrfs@patchwork.kernel.org>);
	Thu, 2 Sep 2010 01:47:09 -0400
Received: from cn.fujitsu.com ([222.73.24.84]:60368 "EHLO
	song.cn.fujitsu.com"
	rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP
	id S1752314Ab0IBFrG (ORCPT <rfc822;linux-btrfs@vger.kernel.org>);
	Thu, 2 Sep 2010 01:47:06 -0400
Received: from tang.cn.fujitsu.com (tang.cn.fujitsu.com [10.167.250.3])
	by song.cn.fujitsu.com (Postfix) with ESMTP id 977FE17011C;
	Thu,  2 Sep 2010 13:46:55 +0800 (CST)
Received: from fnst.cn.fujitsu.com (tang.cn.fujitsu.com [127.0.0.1])
	by tang.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id o825hUPs022408;
	Thu, 2 Sep 2010 13:43:30 +0800
Received: from [10.167.141.211] (unknown [10.167.141.211])
	by fnst.cn.fujitsu.com (Postfix) with ESMTPA id C884214C030;
	Thu,  2 Sep 2010 13:48:15 +0800 (CST)
Message-ID: <4C7F3A31.4070806@cn.fujitsu.com>
Date: Thu, 02 Sep 2010 13:46:25 +0800
From: Miao Xie <miaox@cn.fujitsu.com>
Reply-To: miaox@cn.fujitsu.com
User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US;
	rv:1.9.1.9) Gecko/20100413 Fedora/3.0.4-2.fc13 Thunderbird/3.0.4
MIME-Version: 1.0
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Theodore Ts'o" <tytso@mit.edu>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	Chris Mason <chris.mason@oracle.com>, Yan Zheng <zheng.yan@oracle.com>
CC: Linux Kernel <linux-kernel@vger.kernel.org>,
	Linux Btrfs <linux-btrfs@vger.kernel.org>,
	Linux Ext4 <linux-ext4@vger.kernel.org>
Subject: [PATCH 3/3] x86_64/lib: improve the performance of memmove
Sender: linux-btrfs-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-btrfs.vger.kernel.org>
X-Mailing-List: linux-btrfs@vger.kernel.org
X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by
	milter-greylist-4.2.3 (demeter1.kernel.org [140.211.167.41]);
	Thu, 02 Sep 2010 05:51:25 +0000 (UTC)


diff --git a/arch/x86/lib/memmove_64.c b/arch/x86/lib/memmove_64.c
index 0a33909..3640232 100644
--- a/arch/x86/lib/memmove_64.c
+++ b/arch/x86/lib/memmove_64.c
@@ -4,17 +4,17 @@
 #define _STRING_C
 #include <linux/string.h>
 #include <linux/module.h>
+#include <linux/memcopy.h>
 
 #undef memmove
 void *memmove(void *dest, const void *src, size_t count)
 {
-	if (dest < src) {
+	if (dest - src >= count) {	/* *Unsigned* compare! */
 		return memcpy(dest, src, count);
 	} else {
-		char *p = dest + count;
-		const char *s = src + count;
-		while (count--)
-			*--p = *--s;
+		unsigned long dstp = (unsigned long)dest;
+		unsigned long srcp = (unsigned long)src;
+		mem_copy_bwd(dstp, srcp, count);
 	}
 	return dest;
 }