From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:59636)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <alex@alex.org.uk>) id 1VHEwZ-00033q-Aw
	for qemu-devel@nongnu.org; Wed, 04 Sep 2013 11:24:32 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <alex@alex.org.uk>) id 1VHEwY-0001DH-BO
	for qemu-devel@nongnu.org; Wed, 04 Sep 2013 11:24:31 -0400
Received: from mail.avalus.com ([2001:41c8:10:1dd::10]:39893)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <alex@alex.org.uk>) id 1VHEwY-0001D6-5d
	for qemu-devel@nongnu.org; Wed, 04 Sep 2013 11:24:30 -0400
Date: Wed, 04 Sep 2013 16:24:20 +0100
From: Alex Bligh <alex@alex.org.uk>
Message-ID: <A35D54FFEC699EB4F69642B7@nimrod.local>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Subject: [Qemu-devel] When does live migration give up?
Reply-To: Alex Bligh <alex@alex.org.uk>
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/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: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: qemu-devel@nongnu.org
Cc: Alex Bligh <alex@alex.org.uk>

We have seen a situation when migrating about 50 VMs at once where some
of them fail. I think this is because they are dirtying pages faster than
they can be transmitted.

What algorithm controls when migration fails in this way, and is it
tunable?

I am fully aware one answer to this question is "do not attempt to
migrate 50 busy VMs through a single 1GB/s NIC".

-- 
Alex Bligh