From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=56489 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PqRlg-00081q-63 for qemu-devel@nongnu.org; Fri, 18 Feb 2011 09:57:13 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PqRlf-0006Pr-5B for qemu-devel@nongnu.org; Fri, 18 Feb 2011 09:57:12 -0500 Received: from e33.co.us.ibm.com ([32.97.110.151]:40171) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PqRle-0006PX-Vx for qemu-devel@nongnu.org; Fri, 18 Feb 2011 09:57:11 -0500 Received: from d03relay03.boulder.ibm.com (d03relay03.boulder.ibm.com [9.17.195.228]) by e33.co.us.ibm.com (8.14.4/8.13.1) with ESMTP id p1IEogNi016500 for ; Fri, 18 Feb 2011 07:50:42 -0700 Received: from d03av05.boulder.ibm.com (d03av05.boulder.ibm.com [9.17.195.85]) by d03relay03.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p1IEv3wj112982 for ; Fri, 18 Feb 2011 07:57:03 -0700 Received: from d03av05.boulder.ibm.com (loopback [127.0.0.1]) by d03av05.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p1IEv2c6018658 for ; Fri, 18 Feb 2011 07:57:02 -0700 Message-ID: <4D5E88BD.3050006@linux.vnet.ibm.com> Date: Fri, 18 Feb 2011 08:57:01 -0600 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] [RFC][PATCH v6 00/23] virtagent: host/guest RPC communication agent References: <1295270117-24760-1-git-send-email-mdroth@linux.vnet.ibm.com> <4D5BF581.3050803@redhat.com> <4D5C07CB.4040709@linux.vnet.ibm.com> <4D5CDBD0.2060900@redhat.com> <4D5D3331.1000707@linux.vnet.ibm.com> <4D5E69EB.5040805@redhat.com> <4D5E7D35.7090207@linux.vnet.ibm.com> <4D5E8291.7020900@redhat.com> In-Reply-To: <4D5E8291.7020900@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jes Sorensen Cc: agl@linux.vnet.ibm.com, stefanha@linux.vnet.ibm.com, markus_mueller@de.ibm.com, marcel.mittelstaedt@de.ibm.com, Michael Roth , qemu-devel@nongnu.org, ryanh@us.ibm.com, abeekhof@redhat.com, Luiz Capitulino On 02/18/2011 08:30 AM, Jes Sorensen wrote: > On 02/18/11 15:07, Anthony Liguori wrote: > >> On 02/18/2011 06:45 AM, Jes Sorensen wrote: >> >>> It may not be so fundamental, but it still makes me wary. XMLRPC >>> handling is quite high level and introduces the potential of errors that >>> are outside of our direct control. Personally I don't see the big >>> benefit of having virtagent terminate in QEMU, >>> >> Live migration. If it's a separate daemon, then live migration gets fugly. >> >> If xmlrpc-c is a PoS, then we ought to look at using something else. >> But let's understand what's happening first before drawing any conclusions. >> > Urgh, I always do my best to pretend that there is no such thing as live > migration :) Never seem to work though :( > > However if there's an agent connection, it could be arranged in a way > allowing the host to reconnect to the guest agent. In that way it really > shouldn't be a big deal as long as our agent commands aren't too complex. > Oh, but they'll be nice and complex :-) What happens if you do a live migration in the middle of doing a live backup? You'll end up with the guest waiting to be told that it's okay to unfreeze itself only to never be told. Terminating in QEMU means we can do intelligent things like delay live migration convergence, save state, etc. Regards, Anthony Liguori > xmlrpc-c is probably fine, but it introduces a layer of complexity which > always makes me worried. > > Cheers, > Jes >