[Intel-gfx] [PATCH 3/3] drm/i915: Replace manual checking for idleness with active_requests counter

[Chris Wilson]

Quoting Chris Wilson (2017-10-08 14:43:22)
> As we emit and retire requests, we track how many are still in flight.
> As we have this knowledge, we can make use of that inside
> i915_gem_evict_something() as a better test to see if the device is
> idle.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

I've just confirmed this was the bug that triggered ENOSPC with
(failure to do) context eviction.

With this fixed, the test times out (because we are now forced to wait
for the fence to be signaled) and so preemption/scheduling is fubar.
I guess we just pencil that in as yet-another-pi-bug.
-Chris