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

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

On Tue, Jun 06, 2023 at 10:46:53PM +0000, Parav Pandit wrote:
> 
> 
> > 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.

could we please speak virtio terms? you are not new in this area..
so this is asking for a way to disable used buffer notifications?
we actually have this with packet vq always and with split
without EVENT_IDX. what is missing?

-- 
MST