From owner-freebsd-threads@FreeBSD.ORG  Wed Nov 17 19:30:02 2004
Return-Path: <owner-freebsd-threads@FreeBSD.ORG>
Delivered-To: freebsd-threads@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP
	id 3C8A716A4CE; Wed, 17 Nov 2004 19:30:02 +0000 (GMT)
Received: from silver.he.iki.fi (helenius.fi [193.64.42.241])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id 8C71543D3F; Wed, 17 Nov 2004 19:30:01 +0000 (GMT)
	(envelope-from pete@he.iki.fi)
Received: from [193.64.42.134] (h86.vuokselantie10.fi [193.64.42.134])
	by silver.he.iki.fi (8.13.1/8.11.4) with ESMTP id iAHJU0LY054202;
	Wed, 17 Nov 2004 21:30:00 +0200 (EET)
	(envelope-from pete@he.iki.fi)
Message-ID: <419BA6BA.4060304@he.iki.fi>
Date: Wed, 17 Nov 2004 21:30:02 +0200
From: Petri Helenius <pete@he.iki.fi>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US;
	rv:1.7.2) Gecko/20040803
X-Accept-Language: en-us, en
MIME-Version: 1.0
To: Daniel Eischen <deischen@freebsd.org>
References: <Pine.GSO.4.43.0411171409360.3786-100000@sea.ntplx.net>
In-Reply-To: <Pine.GSO.4.43.0411171409360.3786-100000@sea.ntplx.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
cc: freebsd-threads@freebsd.org
Subject: Re: mutex performance
X-BeenThere: freebsd-threads@freebsd.org
X-Mailman-Version: 2.1.1
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: Wed, 17 Nov 2004 19:30:02 -0000

Daniel Eischen wrote:

>On Wed, 17 Nov 2004, Petri Helenius wrote:
>
>  
>
>>Do you feel that mutex performance could be improved from the current
>>2-3 million lock/unlock operations per second on uncontested mutexes on
>>~2.4Ghz prescott? Which seems to be about 1000 cycles per lock/unlock.
>>    
>>
>
>I'm not sure what you're trying to say above.
>  
>
I have this:
#include <pthread.h>

main()
{
  register int i;
  pthread_mutexattr_t attr;
  pthread_mutex_t onepacket;

  pthread_mutexattr_init (&attr);
  pthread_mutexattr_settype (&attr,PTHREAD_MUTEX_ERRORCHECK);

  pthread_mutex_init (&onepacket,&attr);

  for (i = 0; i < 20000000;i++)
    {
      pthread_mutex_lock (&onepacket);
      pthread_mutex_unlock (&onepacket);
    }
}

And run it:
 > gcc -O3 -std=c99 -g -march=pentiumpro mutextest.c -o mutextest -lthr
 > time ./mutextest
12.291u 0.000s 0:12.29 100.0%   5+189k 0+0io 0pf+0w
 > gcc -O3 -std=c99 -g -march=pentiumpro mutextest.c -o mutextest -lpthread
 > time ./mutextest
7.008u 0.000s 0:07.01 99.8%     5+230k 0+0io 0pf+0w
 > gcc -O3 -std=c99 -g -march=pentiumpro mutextest.c -o mutextest -lc_r
 > time ./mutextest
5.887u 0.000s 0:05.88 100.0%    5+389k 0+0io 0pf+0w


And I'm wondering how much I need to engineer around mutexes or holding 
them for longer and releasing just before yielding. I'm not saying it 
should/must be better, just trying to ask for the feel where to go.

>I want to change libpthread locks to drop the 80386 support
>and just use the atomic primitives for default mutex types.
>In 6.0, we'll also change all the mutexes, CVs, and semaphores
>so they aren't pointers -- that will save an indirection and
>also allow them to be process shared.
>  
>
Do you have patches or is this on planning stage?

Pete