From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:59491) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Taouj-0003Us-Pb for qemu-devel@nongnu.org; Tue, 20 Nov 2012 09:35:18 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Taoua-000557-3z for qemu-devel@nongnu.org; Tue, 20 Nov 2012 09:35:01 -0500 Received: from mx1.redhat.com ([209.132.183.28]:40987) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TaouZ-00054z-Rc for qemu-devel@nongnu.org; Tue, 20 Nov 2012 09:34:52 -0500 Date: Tue, 20 Nov 2012 14:34:44 +0000 From: "Daniel P. Berrange" Message-ID: <20121120143444.GK3461@redhat.com> References: <1353414712-27072-1-git-send-email-stefanha@redhat.com> <1353414712-27072-9-git-send-email-stefanha@redhat.com> <20121120123708.GI3461@redhat.com> <20121120135002.GA28489@stefanha-thinkpad.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20121120135002.GA28489@stefanha-thinkpad.redhat.com> Subject: Re: [Qemu-devel] [PATCH v2 8/8] virtio-blk: add x-data-plane=on|off performance feature Reply-To: "Daniel P. Berrange" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Kevin Wolf , Anthony Liguori , "Michael S. Tsirkin" , qemu-devel@nongnu.org, khoa@us.ibm.com, Stefan Hajnoczi , Paolo Bonzini , asias@redhat.com On Tue, Nov 20, 2012 at 02:50:02PM +0100, Stefan Hajnoczi wrote: > On Tue, Nov 20, 2012 at 12:37:08PM +0000, Daniel P. Berrange wrote: > > On Tue, Nov 20, 2012 at 01:31:52PM +0100, Stefan Hajnoczi wrote: > > > The virtio-blk-data-plane feature is easy to integrate into > > > hw/virtio-blk.c. The data plane can be started and stopped similar to > > > vhost-net. > > > > > > Users can take advantage of the virtio-blk-data-plane feature using the > > > new -device virtio-blk-pci,x-data-plane=on property. > > > > > > The x-data-plane name was chosen because at this stage the feature is > > > experimental and likely to see changes in the future. > > > > Can you give some indication of how it is likely to change, since > > this has a bearing on any libvirt use of this feature ? > > The following expectations: > > 1. This is an experimental feature. It can be enabled through libvirt > using . > > 2. There is ongoing work to break down the global mutex in QEMU, which > will allow virtio-blk-data-plane functionality to become the > virtio-blk emulation default. At that point no command-line options > will be necessary (migration and image formats will be supported). > > So I think there's no need for libvirt to do anything here. Thanks for clarifying, Kevin / Stefan. Based on this info, we'll do nothing with this in libvirt, in the expection that it'll become the default when QEMU is ready for it. Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|