From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from [140.186.70.92] (port=59776 helo=eggs.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1PnGLC-0004GI-Qv
	for qemu-devel@nongnu.org; Wed, 09 Feb 2011 15:08:44 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <anthony@codemonkey.ws>) id 1PnGLA-0005Tw-Oa
	for qemu-devel@nongnu.org; Wed, 09 Feb 2011 15:08:41 -0500
Received: from mail-fx0-f45.google.com ([209.85.161.45]:47229)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <anthony@codemonkey.ws>) id 1PnGLA-0005Tj-Dq
	for qemu-devel@nongnu.org; Wed, 09 Feb 2011 15:08:40 -0500
Received: by fxm12 with SMTP id 12so599533fxm.4
	for <qemu-devel@nongnu.org>; Wed, 09 Feb 2011 12:08:39 -0800 (PST)
Message-ID: <4D52F418.7070000@codemonkey.ws>
Date: Wed, 09 Feb 2011 21:07:52 +0100
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] Re: [PATCH 2/7] Enable I/O thread and VNC threads
	by default
References: <4D510771.3040309@aurel32.net>
	<4D511221.9030505@siemens.com>	<4D5113D3.9090802@aurel32.net>
	<4D511500.1040303@siemens.com>	<4D5115C2.6060008@aurel32.net>
	<4D51842C.8000209@codemonkey.ws>	<4D5125E2.8090902@aurel32.net>
	<4D5132C3.1040900@redhat.com>	<4D5145A4.1070904@aurel32.net>
	<4D515C6C.9000407@aurel32.net>
	<20110209173523.GJ16429@hall.aurel32.net>
In-Reply-To: <20110209173523.GJ16429@hall.aurel32.net>
Content-Type: text/plain; charset=ISO-8859-15; format=flowed
Content-Transfer-Encoding: 8bit
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Aurelien Jarno <aurelien@aurel32.net>
Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>, Jan Kiszka <jan.kiszka@siemens.com>, Marcelo Tosatti <mtosatti@redhat.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, Anthony Liguori <aliguori@linux.vnet.ibm.com>, Paul Brook <paul@codesourcery.com>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, Paolo Bonzini <pbonzini@redhat.com>, Arun Bharadwaj <arun@linux.vnet.ibm.com>

On 02/09/2011 06:35 PM, Aurelien Jarno wrote:
> On Tue, Feb 08, 2011 at 04:08:28PM +0100, Aurelien Jarno wrote:
>    
>> Aurelien Jarno a écrit :
>>      
>>> Paolo Bonzini a écrit :
>>>        
>>>> On 02/08/2011 12:15 PM, Aurelien Jarno wrote:
>>>>          
>>>>> however
>>>>> it should not be done ignoring all the*current*  drawbacks of the
>>>>> iothread mode. We know them (at least for some of them), so let's try to
>>>>> solve them.
>>>>>            
>>>> Let's also enumerate them.
>>>>
>>>>          
>>>  From what I know:
>>> - performance regression in TCG mode
>>>        
>> I setup an x86_64 guest on an x86_64 host (Intel Xeon E5345). Nothing
>> was running except the standard daemons and the CPU governor was set to
>> "performance" on all CPU. I then compared the network performance using
>> netperf in default mode, through a tap interface and a virtio nic. I got
>> the following results (quite reproducible, std below 0.5):
>> - without IO thread: 107.36 MB/s
>> - with IO thread:     89.93 MB/s
>>
>>      
> And the same test on the code from september 2009:
> - without IO thread: 141.8 MB/s
>    

virtio-net is super finicky regarding mitigation strategies and their 
relationship to the I/O thread.  Different benchmarks will behave 
differently.  virtio-blk is probably a better device to test as you'll 
get much more consistent results across different type of I/O patterns.

Regards,

Anthony Liguori