From owner-freebsd-stable@FreeBSD.ORG  Thu Nov 22 11:44:21 2007
Return-Path: <owner-freebsd-stable@FreeBSD.ORG>
Delivered-To: freebsd-stable@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 9BB8016A468;
	Thu, 22 Nov 2007 11:44:21 +0000 (UTC)
	(envelope-from lol@chistydom.ru)
Received: from hermes.hw.ru (hermes.hw.ru [80.68.240.91])
	by mx1.freebsd.org (Postfix) with ESMTP id 9AEFC13C4EC;
	Thu, 22 Nov 2007 11:44:20 +0000 (UTC)
	(envelope-from lol@chistydom.ru)
Received: from [80.68.244.40] (account a_popov@rbc.ru [80.68.244.40] verified)
	by hermes.hw.ru (CommuniGate Pro SMTP 5.0.13)
	with ESMTPA id 202153338; Thu, 22 Nov 2007 14:43:54 +0300
Message-ID: <47456B71.5040205@chistydom.ru>
Date: Thu, 22 Nov 2007 14:43:45 +0300
From: Alexey Popov <lol@chistydom.ru>
User-Agent: Thunderbird 2.0.0.6 (X11/20070924)
MIME-Version: 1.0
To: Kris Kennaway <kris@FreeBSD.org>
References: <4741905E.8050300@chistydom.ru>	<fhs3s5$knj$1@ger.gmane.org>	<47419AB3.5030008@chistydom.ru>	<fhs7hp$2es$2@ger.gmane.org>
	<4741A7DA.2050706@chistydom.ru> <4741DA15.9000308@FreeBSD.org>
	<47429DB8.7040504@chistydom.ru> <4742ADFE.40902@FreeBSD.org>
	<4742C46A.1060701@chistydom.ru> <47432F77.3030606@FreeBSD.org>
	<474339E9.4080301@FreeBSD.org> <4743629B.9090408@FreeBSD.org>
In-Reply-To: <4743629B.9090408@FreeBSD.org>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Cc: Attilio Rao <attilio@freebsd.org>, freebsd-stable@freebsd.org
Subject: Re: 2 x quad-core system is slower that 2 x dual core on FreeBSD
X-BeenThere: freebsd-stable@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Production branch of FreeBSD source code <freebsd-stable.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-stable>, 
	<mailto:freebsd-stable-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-stable>
List-Post: <mailto:freebsd-stable@freebsd.org>
List-Help: <mailto:freebsd-stable-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-stable>,
	<mailto:freebsd-stable-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 22 Nov 2007 11:44:21 -0000

Hi.

Kris Kennaway wrote:
>>> In the meantime there is unfortunately not a lot that can be done, 
>>> AFAICT.  There is one hack that I will send you later but it is not 
>>> likely to help much.  I will also think about how to track down the 
>>> cause of the contention further (the profiling trace only shows that 
>>> it comes mostly from vget/vput but doesn't show where these are 
>>> called from).
>>
>> Actually this patch might help.  It doesn't replace lockmgr but it 
>> does fix a silly thundering herd behaviour.  It probably needs some 
>> adjustment to get it to apply cleanly (it is about 7 months old), and 
>> I apparently stopped using it because I ran into deadlocks.  It might 
>> be stable enough to at least see how much it helps.
> Try this one instead, it applies to HEAD.  You'll need to manually enter 
> the paths though because of how p4 mangles diffs.
Finally I tried your patch and it seems to help a little.

Now FreeBSD 7-STABLE ULE 8-core server without optimized PHP 
realpath_cache_size (producing 2000+ lstats per request) can handle up 
to ~24 rps as opposed to  max. 17 rps without your patch. %sys never 
grows over %user with your patch. On the server with optimized 
realpath_cache_size there's no visible influence of your patch.

However Linux is still 2 times faster for my workload and there should 
also be another ways for optimization.

With best regards,
Alexey Popov