[igt-dev] [PATCH igt] igt/perf_pmu: Disable all cpus

[Chris Wilson]

Quoting Tvrtko Ursulin (2018-02-21 09:24:46)
> As I said, it would be easy to support opening our PMU regardless on 
> which CPU it currently lives on by wrapping the "try the next cpu" logic 
> in the perf open wrappers. In kernel perf tool for instance does that 
> already.
> 
> I could also change i915 to always try to move to CPU0 if it is 
> available, on any online events. But I am not sure that's in the spirit 
> of things.

Ok, I got lost at why i915 perf requires a specific CPU, it is just that
is part of the perf ABI, right?

> I think making IGT perf open wrapper more robust makes most sense.

Yeah, if it's part of the ABI we shouldn't just expect CPU0. Then
throwing a test of the robust perf open in the midst of online/offline
seems sensible.

I guess we will will end up with a perf open before and after each
stage, and keep the pmu fd around until the end.
-Chris