Re: [Qemu-devel] [PATCH v2 8/8] virtio-blk: add x-data-plane=on|off performance feature

[Stefan Hajnoczi <stefanha@gmail.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 <qemu:commandline>.

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