[Intel-gfx] [PATCH i-g-t v2] tests/perf_pmu: Test busyness reporting in face of GPU hangs

[Chris Wilson]

Quoting Tvrtko Ursulin (2018-02-28 17:15:19)
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> Verify that the reported busyness is in line with what would we expect
> from a batch which causes a hang and gets kicked out from the engine.
> 
> v2: Change to explicit igt_force_gpu_reset instead of guessing when a spin
>     batch will hang. (Chris Wilson)
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

It's nice and quick, yes. However, sometime the opposite is true and you
have to wait for the batch you want to start before pulling the trigger.

I'd put a usleep(100) in there /* Wait for batch to execute */ and we
should put the wait-for-execution ability in igt_spin_t. Unfortunately
that requires MI_STORE_DWORD_IMM (or more creativity) limiting it's
availability.

With the sleep issue addressed (commented upon if nothing else),
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris