RE: [virtio-comment] [PATCH] virtio-net: support per-queue coalescing moderation

[Parav Pandit <parav@nvidia.com>]

> From: Michael S. Tsirkin <mst@redhat.com>
> Sent: Wednesday, February 8, 2023 5:29 PM
> 
> On Wed, Feb 08, 2023 at 10:23:00PM +0000, Parav Pandit wrote:
> > > From: Michael S. Tsirkin <mst@redhat.com>
> > > Sent: Wednesday, February 8, 2023 5:16 PM
> > > > > Not having this feature/command even complicates things now that
> > > > > we are talking about removing the RX and TX from the per vq
> > > > > command, how do you change parameters to all TX queues? to all RX
> queues?
> > > > > we'll need 2 special indexes, so we now need le32 to hold the queue
> index.
> > > > No need for special index.
> > > > How does a driver disable all queues or reset all queues? -> One by one.
> > > > So if user want to change for all TXQ, sw can do it one by one by
> > > > iterating TXQ
> > > vqns.
> > >
> > > I think we can split this effort in two parts:
> > >
> > > 1. add a new command and feature bit 2. drop the old command
> > >
> > >
> > > Looks like there's consensus on 1?  And it looks like Alvaro wants
> > > to work on 1 but not 2. Once that is in Parav can work on 2 if he wants to.
> >
> > 3. rename the current one if there is no sw driver that used it.
> 
> That's probably the worst of all options, silently changing behaviour.
> 
How come? Once #2 is done, only #1 is left and that is equivalent silence.
It is effectively #3. So why not do in same series?

> > May be lets wait for Alvaro's answer if there is any sw that used.
> >
> > Doing #3 would be the simplest for all devices and sw to implement and
> consume respectively.
> >
> > I can work with Alvaro to have 1 and 2 as part of same series as two patches,
> so that we don't have to re-discuss this again.
> > Without that
> > a. negotiating two bits at same time is hard.
> > b. Wording #1 also need to mention about what happens when global is also
> negotiated and device is in partial mode.
> 
> There's no mode, partial or otherwise, in either Alvaro's or my proposal.
It is clearly ambitious spec for some unknown software to be in mixed mode that unlikely to find user for.