On 11/29/2017 5:11 PM, Paolo Bonzini wrote:
On 29/11/2017 05:10, Michael S. Tsirkin wrote:
" Interrupt mode for vhost-user is still not supported in current
implementation. But we are evaluating the necessity now.
That's more or less a spec violation. Guest must get interrupts
if it does not disable them. And it must notify host
if host does not disable notifications.
By that, I mean the transmission from virtio to vhost, if virtio is not
actively sending packets, at vhost side, we can stop polling from that
vhost port (i.e., virtio); if VM wants to send packets, besides putting
packets on virtqueue, it also kicks the backend through pio/mmio.
So no need to modify spec.
I understood that as "the vhost-user server is always using poll mode
for the virtqueues" and cannot use e.g. ioeventfds.
We can change to work like this: stop polling, and wait for the eventfd,
and then get back to polling.
Thanks,
Jianfeng
Thanks,
Paolo
