Re: [virtio-comment] [PATCH v5 1/2] virtio-vsock: add description for datagram type

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Mar 03, 2022 at 03:29:31AM +0000, Bobby Eshleman wrote:
> On Wed, Mar 02, 2022 at 05:09:58PM +0100, Stefano Garzarella wrote:
> > Hi Bobby,
> > Sorry for the delay, but I saw these patches today.
> > Please, can you keep me in CC?
> > 
> 
> Hey Stefano, sorry about that. I'm not sure how I lost your CC on this
> one. I'll make sure you are there moving forward.
> 
> I want to mention that I'm taking a look at
> https://gitlab.com/vsock/vsock/-/issues/1 in parallel with my dgram work
> here. After sending out this series we noticed potential overlap between
> the two issues. The additional dgram queues may become redundant if a
> fairness mechanism that solves issue #1 above also applies to
> connection-less protocols (similar to how the TC subsystem works). I've
> just begun sorting out potential solutions so no hard results yet. Just
> putting on your radar that the proposal here in v5 may be impacted if my
> investigation into issue #1 yields something adequate.


With respect to datagram, there is actually another issue which also
exists for stream but is smaller there - per message overhead is not
accounted for.  For stream we can work around that by copying payload
data.  For datagram we can't as we need to preserve message boundaries.
One way to address that is to add config for host/guest per-message
overhead, and have sender decrement fwd counter by that value for
each message sent.

-- 
MST