From owner-freebsd-threads@FreeBSD.ORG  Sat May 20 01:36:05 2006
Return-Path: <owner-freebsd-threads@FreeBSD.ORG>
X-Original-To: freebsd-threads@freebsd.org
Delivered-To: freebsd-threads@freebsd.org
Received: from localhost.my.domain (localhost [127.0.0.1])
	by hub.freebsd.org (Postfix) with ESMTP id B311016A425
	for <freebsd-threads@freebsd.org>; Sat, 20 May 2006 01:36:04 +0000 (UTC)
	(envelope-from davidxu@freebsd.org)
From: David Xu <davidxu@freebsd.org>
To: freebsd-threads@freebsd.org
Date: Sat, 20 May 2006 09:35:54 +0800
User-Agent: KMail/1.8.2
MIME-Version: 1.0
Content-Type: text/plain;
  charset="us-ascii"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <200605200935.54828.davidxu@freebsd.org>
Subject: optimize msleep with PCATCH flag
X-BeenThere: freebsd-threads@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Threading on FreeBSD <freebsd-threads.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-threads>, 
	<mailto:freebsd-threads-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-threads>
List-Post: <mailto:freebsd-threads@freebsd.org>
List-Help: <mailto:freebsd-threads-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-threads>,
	<mailto:freebsd-threads-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 20 May 2006 01:36:05 -0000

Hi,

Here is a patch to reduce overhead when PCATCH flag is set
for msleep.
http://people.freebsd.org/~davidxu/patch/PCATCH_optimize.patch

I use SUN's mutex ping-pong program to test it, source code
is here: http://people.freebsd.org/~davidxu/bench/pp.c

I have tested it on a dual PIII machine, with command:
./pp -v -s system -n 4
 
Here is the result before and after the patch:

x plain_PCATCH.txt
+ PCATCH_optimized.txt
+--------------------------------------------------------------------------+
|+     +            +    x     ++  +*   xx    x  x         *              x|
|        |__________________A__|M___________M_|______________|             |
+--------------------------------------------------------------------------+
    N           Min           Max        Median           Avg        Stddev
x   8         35311         41714       37750.5         38101     1954.5673
+   8         32191         39802         36179     35670.125      2401.755
Difference at 95.0% confidence
	-2430.88 +/- 2348.35
	-6.38008% +/- 6.1635%
	(Student's t, pooled s = 2189.61)

David Xu