Subject: Re: [RFC] Discuss about an new idea "Vsock over Virtio-net"

From: "Michael S. Tsirkin" <[email-masked]>
Date: Mon, 3 Dec 2018 20:31:45 -0500

On Mon, Dec 03, 2018 at 11:10:58AM +0800, jiangyiwen wrote:
> On 2018/11/30 21:40, Michael S. Tsirkin wrote:
> > On Fri, Nov 30, 2018 at 09:10:03PM +0800, Jason Wang wrote:
> >>
> >> On 2018/11/30 下午8:55, Jason Wang wrote:
> >>>
> >>> On 2018/11/30 下午8:52, Michael S. Tsirkin wrote:
> >>>>>>    If you want to compare it with
> >>>>>> something that would be TCP or QUIC.  The fundamental
> >>>>>> difference between
> >>>>>> virtio-vsock and e.g. TCP is that TCP operates in a packet
> >>>>>> loss environment.
> >>>>>> So they are using timers for reliability, and receiver is
> >>>>>> always free to
> >>>>>> discard any unacked data.
> >>>>> Virtio-net knows nothing above L2, so they are totally
> >>>>> transparent to device
> >>>>> itself. I still don't get why not using virtio-net instead.
> >>>>>
> >>>>>
> >>>>> Thanks
> >>>> Is your question why is virtio-vsock used instead of TCP on top of IP
> >>>> on top of virtio-net?
> >>>>
> >>>>
> >>>
> >>> No, my question is why not do vsock through virtio-net.
> >>>
> >>> Thanks
> >>>
> >>
> >> Just to clarify, it's not about vosck over ethernet, and it's not about
> >> inventing new features or APIs. It's probably something like:
> >>
> >> - Let virtio-net driver probe vsock device and do vosck specific things if
> >> needed to share as much codes.
> >>
> >> - A new kind of sockfd (which is vsock based) for vhost-net for it to do
> >> vsock specific things (hopefully it can be transparent).
> >>
> >> The change should be totally transparent to userspace applications.
> >>
> >> Thanks
> > 
> > Which code is duplicated between virtio vsock and virtio net right now?
> > 
> 
> Hi Michael,
> 
> AFAIK, there is almost no duplicate code between virtio vsock and virtio net now.
> 
> But, if virtio vsock wants to support mergeable rx buffer and multiqueue feature,
> it has some duplicate codes from virtio net. Based on it, we both think vsock
> may use virtio net as a transport channel, in this way, vsock can use some of
> virtio net great features.
> 
> Thanks,
> Yiwen.

What I would do is just copy some code and show a performance
benefit. If that works out it will be clearer which code
should be shared.

-- 
MST