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Date: Thu, 29 Nov 2012 17:19:46 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v4 00/11] virtio: virtio-blk data plane
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Anthony Liguori <aliguori@us.ibm.com>, qemu-devel <qemu-devel@nongnu.org>, Blue Swirl <blauwirbel@gmail.com>, Khoa Huynh <khoa@us.ibm.com>, Stefan Hajnoczi <stefanha@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Asias He <asias@redhat.com>

On Thu, Nov 29, 2012 at 03:48:04PM +0100, Stefan Hajnoczi wrote:
> On Thu, Nov 29, 2012 at 04:09:28PM +0200, Michael S. Tsirkin wrote:
> > On Thu, Nov 29, 2012 at 10:18:59AM +0100, Stefan Hajnoczi wrote:
> > > Michael, Paolo: Are you happy with v4?
> > 
> > Looks pretty clean by itself. I sent some comments but they can be
> > addressed later.  What worries me most is the code duplication with
> > regular virtio.
> > 
> > I see two ways to reduce the maintainance somewhat
> > - split out ring handling code in virtio-blk
> >   to a separate file to make it more obvious which part
> >   is inactive when data plane runs.
> > - share ring processing code with virtio/virtio-blk
> >   (e.g. use callbacks)
> > 
> > Was any thought given to implementing one of these two
> > approaches? 
> 
> Yes, your option #2 is where I'd like to move once threaded memory
> dispatch is working.  I hope we can run virtio.c code in a thread
> outside the global mutex soon.  That way we can kill
> hw/dataplane/vring.[ch].
> 
> Ping Fan Liu has been working on the memory API and device emulation
> stuff that we need in order to eventually use virtio.c outside the
> global mutex.
> 
> Stefan

I guess we can live with this short term.