From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:41979) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TaoDR-0006pZ-Jh for qemu-devel@nongnu.org; Tue, 20 Nov 2012 08:50:23 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TaoDI-0006dK-JR for qemu-devel@nongnu.org; Tue, 20 Nov 2012 08:50:15 -0500 Received: from mail-bk0-f45.google.com ([209.85.214.45]:33742) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TaoDI-0006YP-Bz for qemu-devel@nongnu.org; Tue, 20 Nov 2012 08:50:08 -0500 Received: by mail-bk0-f45.google.com with SMTP id jk13so1405169bkc.4 for ; Tue, 20 Nov 2012 05:50:04 -0800 (PST) Date: Tue, 20 Nov 2012 14:50:02 +0100 From: Stefan Hajnoczi Message-ID: <20121120135002.GA28489@stefanha-thinkpad.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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121120123708.GI3461@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2 8/8] virtio-blk: add x-data-plane=on|off performance feature List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" 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 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. Stefan