[Intel-gfx] [PATCH i-g-t] lib/igt_perf: Find active perf CPU

[Chris Wilson]

Quoting Tvrtko Ursulin (2018-02-21 10:29:57)
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> Instead of assuming PMU runs on CPU0, try all possible CPUs if that is not
> the case. This makes the callers handle fallout from broken tests better,
> as well as sysadmin interventions where callers are not tests.
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>

As a bonus it also helps document the perf_open() call.
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

Are we not allowed to pass cpu=-1 for any/all cpus?
-Chris