[Intel-gfx] [RFC PATCH 3/3] drm/i915: add a new perf configuration execbuf parameter

[Chris Wilson]

Quoting Lionel Landwerlin (2018-10-08 16:18:22)
> We want the ability to dispatch a set of command buffer to the
> hardware, each with a different OA configuration. To achieve this, we
> reuse a couple of fields from the execbuf2 struct (I CAN HAZ
> execbuf3?) to notify what OA configuration should be used for a batch
> buffer. This requires the process making the execbuf with this flag to
> also own the perf fd at the time of execbuf.

Sigh. It's a distinct step from emit_bb_start and should be using
emit_bb_start itself to execute the batch. Use i915_vma_move_to_active
to couple into retirement correctly, and use pin properly.

If you feel emit_bb is doing too much, split it up into primitives
rather than continue to overload it; emit_bb is used and will be used
outside of execbuf.
-Chris