[RFC PATCH 0/8] *** Per context fencing ***

[Gerd Hoffmann]

  Hi,

> Can virtqueues be added dynamically?

No.

> Or can we have
> fixed but enough (e.g., 64) virtqueues?

Well, I wouldn't bet that any specific number is enough.  When gtk
starts rendering using vulkan by default the number of contexts of a
standard gnome desktop will be pretty high I guess ...

We can have a host-configurable number of virtqueues.  Typically the
guest can figure the number of available queues from config space.  One
common usage pattern (seen in block/net devices) is to have the number
of virtqueues equal the number of vcpus, so each vcpu has dedicated
virtqueue.

For virtio-gpu it is probably more useful to bind contexts to
virtqueues.  As long as we have enough virtqueues each context can
have its own.  Once we run out of virtqueues we have to start sharing.

On the host side it probably makes sense to have one process per
virtqueue.

cheers,
  Gerd