[Intel-gfx] [RFC PATCH 1/5] drm/doc/rfc: i915 GuC submission / DRM scheduler integration plan

[Daniel Stone]

Hi,

On Tue, 11 May 2021 at 15:34, Daniel Vetter <daniel at ffwll.ch> wrote:
> On Thu, May 06, 2021 at 10:30:45AM -0700, Matthew Brost wrote:
> > +No major changes are required to the uAPI for basic GuC submission. The only
> > +change is a new scheduler attribute: I915_SCHEDULER_CAP_STATIC_PRIORITY_MAP.
> > +This attribute indicates the 2k i915 user priority levels are statically mapped
> > +into 3 levels as follows:
> > +
> > +* -1k to -1 Low priority
> > +* 0 Medium priority
> > +* 1 to 1k High priority
> > +
> > +This is needed because the GuC only has 4 priority bands. The highest priority
> > +band is reserved with the kernel. This aligns with the DRM scheduler priority
> > +levels too.
>
> Please Cc: mesa and get an ack from Jason Ekstrand or Ken Graunke on this,
> just to be sure.

A reference to the actual specs this targets would help. I don't have
oneAPI to hand if it's relevant, but the two in graphics world are
https://www.khronos.org/registry/EGL/extensions/IMG/EGL_IMG_context_priority.txt
and https://www.khronos.org/registry/vulkan/specs/1.2-extensions/html/chap5.html#devsandqueues-priority
- both of them pretty much say that the implementation may do anything
or nothing at all, so this isn't a problem for spec conformance, only
a matter of user priority (sorry).

Cheers,
Daniel