From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from [140.186.70.92] (port=38665 helo=eggs.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1PNpyk-0003eS-H2
	for qemu-devel@nongnu.org; Wed, 01 Dec 2010 11:56:27 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <anthony@codemonkey.ws>) id 1PNpyj-0004AJ-88
	for qemu-devel@nongnu.org; Wed, 01 Dec 2010 11:56:26 -0500
Received: from mail-qy0-f173.google.com ([209.85.216.173]:51751)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <anthony@codemonkey.ws>) id 1PNpyj-0004A4-5E
	for qemu-devel@nongnu.org; Wed, 01 Dec 2010 11:56:25 -0500
Received: by qyk1 with SMTP id 1so2879434qyk.4
	for <qemu-devel@nongnu.org>; Wed, 01 Dec 2010 08:56:24 -0800 (PST)
Message-ID: <4CF67E35.2060505@codemonkey.ws>
Date: Wed, 01 Dec 2010 10:56:21 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
References: <cover.1290552026.git.quintela@redhat.com>	<411b3f89b6b79b429686bd1b1fa188ba55b6c6f7.1290552026.git.quintela@redhat.com>	<4CF45DE0.8020701@codemonkey.ws>
	<m3r5e2vpgf.fsf@trasno.mitica>	<4CF65FBB.3020406@redhat.com>
	<m3lj49xzhp.fsf@trasno.mitica>	<4CF66FEB.7030602@codemonkey.ws>
	<m3fwuhxxxt.fsf@trasno.mitica> <4CF678E0.9070904@codemonkey.ws>
	<4CF67B19.9000308@redhat.com> <4CF67C9C.5000403@codemonkey.ws>
	<4CF67D65.8040408@redhat.com>
In-Reply-To: <4CF67D65.8040408@redhat.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Subject: [Qemu-devel] Re: [PATCH 10/10] Maintaing number of dirty pages
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: Avi Kivity <avi@redhat.com>
Cc: qemu-devel@nongnu.org, Juan Quintela <quintela@redhat.com>

On 12/01/2010 10:52 AM, Avi Kivity wrote:
> On 12/01/2010 06:49 PM, Anthony Liguori wrote:
>>> We need actual measurements instead of speculations.
>>
>>
>> Yes, I agree 100%.  I think the place to start is what I suggested in 
>> a previous note in this thread, we need to measure actual stall time 
>> in the guest.
>
> I'd actually start at the host.  How much time does 
> ioctl(KVM_GET_DIRTY_LOG) take?  What's the percentage of time 
> qemu_mutex is held?

The question is, what really are the symptoms of the problem.  It's not 
necessarily a bad thing if KVM_GET_DIRTY_LOG takes a long while 
qemu_mutex is held.

Is the problem that the monitor responds slowly?  Is the problem that 
the guest isn't consistently getting execution time?  Is the proper 
simply that the guest isn't getting enough total execution time?

I think we need to identify exactly what the problem is before we look 
for sources.

Regards,

Anthony Liguori