From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40544) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X5JcV-0002Tn-BA for qemu-devel@nongnu.org; Thu, 10 Jul 2014 15:03:10 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1X5JcK-0003JC-EJ for qemu-devel@nongnu.org; Thu, 10 Jul 2014 15:03:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2100) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X5JcK-0003Iv-4z for qemu-devel@nongnu.org; Thu, 10 Jul 2014 15:02:52 -0400 Date: Thu, 10 Jul 2014 20:02:43 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20140710190242.GL2627@work-vm> References: <1404495717-4239-1-git-send-email-dgilbert@redhat.com> <1404495717-4239-17-git-send-email-dgilbert@redhat.com> <53BAF7EC.7090809@redhat.com> <20140707202327.GA2568@work-vm> <53BEBCB0.1000002@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53BEBCB0.1000002@redhat.com> Subject: Re: [Qemu-devel] [PATCH 16/46] Add migration-capability boolean for postcopy-ram. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: aarcange@redhat.com, yamahata@private.email.ne.jp, lilei@linux.vnet.ibm.com, quintela@redhat.com, qemu-devel@nongnu.org * Paolo Bonzini (pbonzini@redhat.com) wrote: > Il 07/07/2014 22:23, Dr. David Alan Gilbert ha scritto: > >I think what I need to do for that is: > > 1) As for precopy add the option not to start the destination CPU on entry to postcopy; > > I think that's OK, because we can carry on in postcopy mode even if the destination > > CPU isn't running, we just won't generate page requests. > > > >Admittedly I don't quite understand how (1) is supposed to interact with device > >state. > > This is just passing "-S" on the destination side. Device state is treated > the same as without "-S" and can still generate page requests. The only > difference is whether you have a vm_start() or not. Good, that sounds easy enough. > I think it should be possible to restart the VM on the source side after > postcopy migration, as long as migration has failed or has been canceled. > Whether that makes sense or causes dire disk corruption depends on the > particular scenario, but then the same holds for precopy and we don't try at > all to prevent "cont" at the end of migration. It makes it much easier for > libvirt to restart the source if it cannot continue on the destination. Interesting; Andrea fell into accidentally starting his source and was somewhat surprised. I was just going to add the RAN_STATE_MEMORY_STALE that Lei Li added in the exec-migration patchset. Dave > > Paolo -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK