[Intel-gfx] [PATCH v2 9/9] drm/i915/scheduler: Support user-defined priorities

[Chris Wilson]

On Thu, Oct 27, 2016 at 03:05:16PM +0100, Chris Wilson wrote:
> Use a priority stored in the context as the initial value when
> submitting a request. This allows us to change the default priority on a
> per-context basis, allowing different contexts to be favoured with GPU
> time at the expense of lower importance work. The user can adjust the
> context's priority via I915_CONTEXT_PARAM_PRIORITY, with more positive
> values being higher priority (they will be serviced earlier, after their
> dependencies have been resolved). Any prerequisite work for an execbuf
> will have its priority raised to match the new request as required.

Not in mesa yet, but use case would in supporting EGL_IMG_context_priority
https://www.khronos.org/registry/egl/extensions/IMG/EGL_IMG_context_priority.txt

	EGL_CONTEXT_PRIORITY_LEVEL_IMG determines the priority level of
        the context to be created. This attribute is a hint, as an
        implementation may not support multiple contexts at some
        priority levels and system policy may limit access to high
        priority contexts to appropriate system privilege level. The
        default value for EGL_CONTEXT_PRIORITY_LEVEL_IMG is
        EGL_CONTEXT_PRIORITY_MEDIUM_IMG."

i.e.
PRIORITY_HIGH -> 1023 [privileged, will failback to 0]
PRIORITY_MED -> 0 [default]
PRIORITY_LOW -> -1023

Does anyone has a real use for this? On the transcode side?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre