Re: [virtio-comment] RE: [virtio-dev] [PATCH] virtio-net: Fix and update VIRTIO_NET_F_NOTF_COAL feature

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

On Wed, Feb 08, 2023 at 05:30:28PM +0000, Parav Pandit wrote:
> > From: Michael S. Tsirkin <mst@redhat.com>
> > Sent: Tuesday, February 7, 2023 9:18 AM
> 
> > > Why migration generate too many spurious interrupts?
> > 
> > Because, you might want to migrate from hardware with to hardware without
> > coalescing features. So you just tell guest "sure I will coalesce" but in fact send
> > interrupts normally.
> 
> For the hardware that has fake coalescing, HV wouldn't know it anyway without doing pre verification.
> And HV may not migrate in such case for best experience.
> HV may choose to migrate with low accuracy as you say, which is fine.
> 
> But the spec guidance for the device implementations is to promote some reasonable level of accuracy.
> Hard to define in words here.
> Best effort is wide spectrum of range. :)
> 
> Typically, we say in the spec as SHOULD. 
> So, lets skip the best-effort wording and stick to SHOULD part like rest of the spec.

I think the point of best-effort is that driver must handle interrupts
that arrive earlier. This is how we used it elsewhere. What else does
it include in your opinion that we absolutely must exclude?
I feel it's a good fit for a non-conformance section which is
by nature a bit informal.

For a conformance section SHOULD is indeed a good fit.

-- 
MST


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