RE: [virtio-comment] [PATCH requirements 4/7] net-features: Add notification coalescing requirements

[Parav Pandit <parav@nvidia.com>]

> From: Michael S. Tsirkin <mst@redhat.com>
> Sent: Tuesday, June 6, 2023 6:37 PM

> >  # 3. Requirements
> >  ## 3.1 Device counters
> > @@ -143,3 +144,10 @@ struct vnet_rx_completion {  7. The device should
> > be able to indicate when a full page buffer is consumed,
> >     which can be recycled by the driver when the packets from the completed
> >     page is fully consumed.
> > +
> > +## 3.3 Virtqueue notification coalescing re-enable support 1. Tx and
> > +Rx virtqueue notification coalescing should auto-disable on
> > +   notification reporting to the driver. The driver should be able to enable
> > +   coalescing after processing the packets per VQ. This ensures that when
> > +   networking stack decides to poll, no new notifications are generated when
> > +   per VQ notification coalescing is used.
> 
> I don't know what does auto-disable and enable coalescing mean.
> Does this refer to VIRTIO_NET_F_NOTF_COAL?

> what is the problem this is trying to solve?
>
Current driver when uses F_VQ_NOTF_COAL, and polling, it still receives the event (interrupt) from the device, because the time is always running.
(event is not auto disabled on generation of the event).
So number of interrupts are not fully controlled yet by the driver.