[virtio-dev] RE: RE: About custom device counter

Parav Pandit
2023-06-19T20:41:04Z

> From: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> Sent: Thursday, June 15, 2023 2:35 AM

> > Debug counters are useful to have.
> > I agree that they may be vendor specific.
> > We often try to abstract and define as much as vendor neutral as possible.
> >
> > So we should probably first put our efforts to see if more than one vendor can
> use it.
>
> I agree.
>
> >
> > Assuming there is some vendor specific counters, I imagine to come from a
> separate vendor specific query command.
> > This is to keep standard counters to avoid mixing with vend_specific.
>
> Yes, I agree that these are two separate channels.
>
> But I don't think we need to wait for the first job to finish.
>
I am saying if you have a counter in mind, lets discuss if we can generalize it, and if we can it falls in the first general bucket.
If we cannot it falls in second vendor specific bucket.

> It is conceivable that standard counters will be displayed on ethtool in the
> future. For counters from different manufacturers, we can display them in
> /sys/class/net/eth0/vendor_couters.
>
I understood that you want to show device specific counters.
We can avoid bringing up the sw interface for a moment.
For above specific suggestion, vendor counters in sysfs for sure will not be acceptable as no vendor specific sysfs can exist anymore.

One can implement devlink health reporting counters as needed.

> Here we can tell the user that these are only for the current device, and may
> change during the migration process.
>
Sure.

>
> >
> > > Of course I know that doing this might hurt migration. But what I
> > > want to say is, why does it affect live migration? These counters we
> > > plan to give to users through ethtool -S, and some changes have
> > > taken place in the ethtool counters output by users. Does this have
> > > any practical impact? Or do we directly use some other output in a
> > > way, we can clearly tell the user that these counters may change
> > > during the migration process. For example, the driver is migrated to
> > > some new devices. These devices support some new counters. I think
> > > users should be able to see these new counters. These new counters may be
> the purpose of the migration.
> >
> > Counters which are well defined non-vendor specific should be able to
> migrate to destination on best effort basis.
> > For well defined counters if device A at src support N counters, on migrated
> destination, it should be N.
> > This should be able to achieve with feature provisioning infra via group owner
> command.
>
> Yes, for standard counters.
>
> >
> > >
> > > We don't need to support live migration at this point.
> > When done on best effort level, infra exists, vendor has ability to
> incrementally implement it.
>
>
> For the standard counters, the manufacturer will be very willing to use it. I just
> want to introduce the capabilities of the manufacturer's customized.
>
Lets try to generalize first and if we fail consider the vendor specific counters.