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From: Miao Xie <miaox@cn.fujitsu.com>
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@dilg
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
Date: Thu, 02 Sep 2010 13:46:25 +0800	[thread overview]
Message-ID: <4C7F3A31.4070806@cn.fujitsu.com> (raw)

This patch improved the performance of memmove on x86_64 by using mem_copy_bwd()
instead of byte copy. But x86_64's memcpy is quite fast, so I didn't change it.

I have tested this patchset by doing 500 bytes memory copy for 50000 times
on my x86_64 box:
			memmove
2.6.36-rc1		2s 610445us	
2.6.36-rc1 + patch	0s 257358us

After appling this patchset, the performance of the file creation and deletion
on some filesystem become better. I have tested it with the following benchmark
tool on my x86_64 box.
  http://marc.info/?l=linux-btrfs&m=128212635122920&q=p3

Test steps:
# ./creat_unlink 50000

The result(Total time):
Ext4:
		2.6.36-rc1	2.6.36-rc1 + patchset
file creation	0.771240	0.698983		9.4%UP
file deletion	0.459065	0.425530		7.3%UP


Btrfs:
		2.6.36-rc1	2.6.36-rc1 + patchset
file creation	0.966807	0.947592		1.9%UP
file deletion	1.355671	1.217787		10.2%UP 

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
---
 arch/x86/lib/memmove_64.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

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;
 }
-- 
1.7.0.1

WARNING: multiple messages have this Message-ID (diff)
From: Miao Xie <miaox@cn.fujitsu.com>
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
Date: Thu, 02 Sep 2010 13:46:25 +0800	[thread overview]
Message-ID: <4C7F3A31.4070806@cn.fujitsu.com> (raw)

This patch improved the performance of memmove on x86_64 by using mem_copy_bwd()
instead of byte copy. But x86_64's memcpy is quite fast, so I didn't change it.

I have tested this patchset by doing 500 bytes memory copy for 50000 times
on my x86_64 box:
			memmove
2.6.36-rc1		2s 610445us	
2.6.36-rc1 + patch	0s 257358us

After appling this patchset, the performance of the file creation and deletion
on some filesystem become better. I have tested it with the following benchmark
tool on my x86_64 box.
  http://marc.info/?l=linux-btrfs&m=128212635122920&q=p3

Test steps:
# ./creat_unlink 50000

The result(Total time):
Ext4:
		2.6.36-rc1	2.6.36-rc1 + patchset
file creation	0.771240	0.698983		9.4%UP
file deletion	0.459065	0.425530		7.3%UP


Btrfs:
		2.6.36-rc1	2.6.36-rc1 + patchset
file creation	0.966807	0.947592		1.9%UP
file deletion	1.355671	1.217787		10.2%UP 

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
---
 arch/x86/lib/memmove_64.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

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;
 }
-- 
1.7.0.1

             reply	other threads:[~2010-09-02  5:46 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-02  5:46 Miao Xie [this message]
2010-09-02  5:46 ` [PATCH 3/3] x86_64/lib: improve the performance of memmove Miao Xie
  -- strict thread matches above, loose matches on Subject: below --
2010-09-01 10:36 Miao Xie
2010-09-01 10:36 Miao Xie
2010-09-01 10:36 Miao Xie

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