[Intel-gfx] [PATCH 1/5] drm/i915: Track per-context engine busyness

[Chris Wilson]

Quoting Tvrtko Ursulin (2019-12-16 12:07:00)
> @@ -1389,6 +1415,9 @@ static void execlists_submit_ports(struct intel_engine_cs *engine)
>                 write_desc(execlists,
>                            rq ? execlists_update_context(rq) : 0,
>                            n);
> +
> +               if (n == 0)
> +                       intel_context_stats_start(&rq->hw_context->stats);

Too early? (Think preemption requests that may not begin for a few
hundred ms.) Mark it as started on promotion instead (should be within a
few microseconds, if not ideally a few 10 ns)? Then you will also have
better symmetry in process_csb, suggesting that we can have a routine
that takes the current *execlists->active with fewer code changes.
-Chris