[RFC 3/3] drm/i915/gt: Export device and per-process runtimes via procfs

[Emil Velikov]

On Fri, 12 Feb 2021 at 15:16, Chris Wilson <chris at chris-wilson.co.uk> wrote:
>
> Quoting Emil Velikov (2021-02-12 14:57:56)
> > Hi Chris,
> >
> > On Thu, 4 Feb 2021 at 12:11, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > >
> > > Register with /proc/gpu to provide the client runtimes for generic
> > > top-like overview, e.g. gnome-system-monitor can use this information to
> > > show the per-process multi-GPU usage.
> > >
> > Exposing this information to userspace sounds great IMHO and like the
> > proposed "channels" for the device engines.
> > If it were me, I would have the channel names a) exposed to userspace
> > and b) be a "fixed set".
>
> - Total
> - Graphics
> - Compute
> - Unified
> - Video
> - Copy
> - Display
> - Other
>
> Enough versatility for the foreseeable future?
> But plan for extension.
>
With a bit of documentation about "unified" (is it a metric also
counted towards any of the rest) it would be perfect.
For future extension one might consider splitting video into
encoder/decoder/post-processing.

> The other aspect then is the capacity of each channel. We can keep it
> simple as the union/average (whichever the driver has to hand) runtime in
> nanoseconds over all IP blocks within a channel.

Not sure what you mean with capacity. Are you referring to having
multiple instances of the same engine (say 3 separate copy engines)?
Personally I'm inclined to keep these separate entries, since some
hardware can have multiple ones.

For example - before the latest changes nouveau had 8 copy engines,
3+3 video 'generic' video (enc,dec)oder engines, amongst others.

Thanks
Emil