From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1KqT8q-0002AF-RQ
	for qemu-devel@nongnu.org; Thu, 16 Oct 2008 09:43:52 -0400
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1KqT8o-00028S-VB
	for qemu-devel@nongnu.org; Thu, 16 Oct 2008 09:43:52 -0400
Received: from [199.232.76.173] (port=50369 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1KqT8o-00028H-Pr
	for qemu-devel@nongnu.org; Thu, 16 Oct 2008 09:43:50 -0400
Received: from yw-out-1718.google.com ([74.125.46.152]:4149)
	by monty-python.gnu.org with esmtp (Exim 4.60)
	(envelope-from <anthony@codemonkey.ws>) id 1KqT8o-00087C-AG
	for qemu-devel@nongnu.org; Thu, 16 Oct 2008 09:43:50 -0400
Received: by yw-out-1718.google.com with SMTP id 6so657328ywa.82
	for <qemu-devel@nongnu.org>; Thu, 16 Oct 2008 06:43:49 -0700 (PDT)
Message-ID: <48F74511.8080700@codemonkey.ws>
Date: Thu, 16 Oct 2008 08:43:45 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] Re: [RFC] Disk integrity in QEMU
References: <48EE38B9.2050106@codemonkey.ws>	<20081013170610.GF21410@us.ibm.com>	<6A99DBA5-D422-447D-BF9D-019FB394E6C6@lvivier.info>	<20081013194328.GJ21410@us.ibm.com>	<148FE536-F397-4F51-AE3F-C94E4F1F5D4E@lvivier.info>	<20081013210509.GL21410@us.ibm.com>	<1224076205.4150.17.camel@frecb07144>
	<1224152681.4168.5.camel@frecb07144>
In-Reply-To: <1224152681.4168.5.camel@frecb07144>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Reply-To: qemu-devel@nongnu.org
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.gnu.org/pipermail/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: qemu-devel@nongnu.org
Cc: Chris Wright <chrisw@redhat.com>, Mark McLoughlin <markmc@redhat.com>, Ryan Harper <ryanh@us.ibm.com>

Laurent Vivier wrote:
> Hi,
>
> I've made a benchmark using a database:
> mysql and sysbench in OLTP mode.
>
> cache=off seems to be the best choice in this case...
>   

It would be interesting for you to run the same workload under KVM.

> mysql database
> http://sysbench.sourceforge.net
>
> sysbench --test=oltp
>
> 200,000 requests on 2,000,000 rows table.
>
>                  | total time | per-request stat (ms) |
>                  |  (seconds) |  min  |  avg  |  max  |
> -----------------+------------+-------+-------+-------+
> baremetal        |   208.6237 |   2.5 |  16.7 | 942.6 |
> -----------------+------------+-------+-------+-------+
> cache=on         |   642.2962 |   2.5 |  51.4 | 326.9 |
> -----------------+------------+-------+-------+-------+
> cache=on,O_DSYNC |   646.6570 |   2.7 |  51.7 | 347.0 |
> -----------------+------------+-------+-------+-------+
> cache=off        |   635.4424 |   2.9 |  50.8 | 399.5 |
> -----------------+------------+-------+-------+-------+
>   

Because you're talking about 1/3% of native performance.  This means 
that you may be dominated by things like CPU overhead verses actual IO 
throughput.

Regards,

Anthony Liguori

> Laurent
>