From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NUQiE-0005fC-4N for qemu-devel@nongnu.org; Mon, 11 Jan 2010 15:18:06 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NUQi9-0005d4-39 for qemu-devel@nongnu.org; Mon, 11 Jan 2010 15:18:05 -0500 Received: from [199.232.76.173] (port=51128 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NUQi8-0005cy-W9 for qemu-devel@nongnu.org; Mon, 11 Jan 2010 15:18:01 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50742) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NUQi8-00039B-Bz for qemu-devel@nongnu.org; Mon, 11 Jan 2010 15:18:00 -0500 Date: Mon, 11 Jan 2010 22:15:01 +0200 From: "Michael S. Tsirkin" Subject: Re: [Qemu-devel] [PATCH-RFC 00/13] vhost-net: preview Message-ID: <20100111201501.GA15944@redhat.com> References: <20100111171641.GA11936@redhat.com> <20100111200910.GB10230@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100111200910.GB10230@redhat.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: qemu-devel@nongnu.org On Mon, Jan 11, 2010 at 08:09:10PM +0000, Daniel P. Berrange wrote: > On Mon, Jan 11, 2010 at 07:16:42PM +0200, Michael S. Tsirkin wrote: > > Here's an untested patchset with vhost support for upstream qemu. Note > > that you should not expect performance gains from vhost unless in-kernel > > irqchip is enabled (which is not in upstream qemu now). Since adding > > vhost involves quite a bit of infrastructure, I thought it makes sense > > to send an RFC already, so that interested parties can review it. In > > particular, command line and help text need to be finalized early to so > > that management can start looking on supporting the feature. This patch > > has all bits besides migration filled in. Also missing is packet socket > > backend: another team is now working on this. > > Can you clarify a question about migration for me. Is it possible to > live migrate a guest configured with tap + bridge on one machine over > to another where it is launched with vhost + bridge, and vice-versa. Long term, this will be possible without any tweaks. Currently vhost does not support mergeable buffers feature which thus needs to be disabled on both sides for migration to work. Work is underway to add this support. > In other words does this vhost support have any guest visible impact > that would cause migraiton compatability problems, or it is purely a > host side optimization like vnet_hdr was ? > > Regards, > Daniel vnet_hdr has guest visible impact. > -- > |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| > |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| > |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| > |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|