From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from [140.186.70.92] (port=59442 helo=eggs.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1Pau8p-0002sw-BC
	for qemu-devel@nongnu.org; Thu, 06 Jan 2011 13:00:52 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1Pau8o-0005wS-3O
	for qemu-devel@nongnu.org; Thu, 06 Jan 2011 13:00:51 -0500
Received: from mx1.redhat.com ([209.132.183.28]:58563)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1Pau8n-0005w9-Sy
	for qemu-devel@nongnu.org; Thu, 06 Jan 2011 13:00:50 -0500
Date: Thu, 6 Jan 2011 20:00:31 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20110106180031.GB28917@redhat.com>
References: <AANLkTimrVzxcwxrTya0=Av2NDfbP_2tEvr6+vPjQzwJx@mail.gmail.com>
	<20101213161219.GA6715@redhat.com>
	<AANLkTikXEMUFdP-KUf13msbVf6Tpq2vU7=6k9bEVsUBQ@mail.gmail.com>
	<AANLkTimWANc_YOeguo=q45Mh5JyMzBLAuhu_u4C+pQoY@mail.gmail.com>
	<20101213185251.GA9554@redhat.com>
	<AANLkTi=jYxX=LWHgR05VqB3ZvamhRZJcRQ9XFmvbaUdE@mail.gmail.com>
	<20101215121423.GB1746@redhat.com>
	<AANLkTim9Nsyo97y+mw8q3VaZBhGV80QAYvkikiaTQDON@mail.gmail.com>
	<20101219144953.GA20565@redhat.com>
	<AANLkTinxEbZnmFcM7z4=5b=FnRDFdOY3O9Tt6eMactOY@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <AANLkTinxEbZnmFcM7z4=5b=FnRDFdOY3O9Tt6eMactOY@mail.gmail.com>
Subject: [Qemu-devel] Re: [PATCH v5 0/4] virtio: Use ioeventfd for virtqueue
	notify
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: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Khoa Huynh <khoa@us.ibm.com>, qemu-devel@nongnu.org

On Thu, Jan 06, 2011 at 04:41:50PM +0000, Stefan Hajnoczi wrote:
> Here are 4k sequential read results (cache=none) to check whether we
> see an ioeventfd performance regression with virtio-blk.
> 
> The idea is to use a small blocksize with an I/O pattern (sequential
> reads) that is cheap and executes quickly.  Therefore we're doing many
> iops and the cost virtqueue kick/notify is especially important.
> We're not trying to stress the disk, we're trying to make the
> difference in ioeventfd=on/off apparent.
> 
> I did 2 runs for both ioeventfd=off and ioeventfd=on.  The results are
> similar: 1% and 2% degradation in MB/s or iops.  We'd have to do more
> runs to see if the degradation is statistically significant, but the
> percentage value is so low that I'm satisfied.
> 
> Are you happy to merge virtio-ioeventfd v6 + your fixups?

BTW if you could do some migration stress-testing too,
would be nice. autotest has support for it now.

-- 
MST