[Intel-gfx] [PATCH v2] drm/i915/pmu: Report frequency as zero while GPU is sleeping

[Tvrtko Ursulin]

On 06/12/2019 12:32, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2019-11-29 10:54:36)
>> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>>
>> We used to report the minimum possible frequency as both requested and
>> active while GPU was in sleep state. This was a consequence of sampling
>> the value from the "current frequency" field in our software tracking.
>>
>> This was strictly speaking wrong, but given that until recently the
>> current frequency in sleeping state used to be equal to minimum, it did
>> not stand out sufficiently to be noticed as such.
>>
>> After some recent changes have made the current frequency be reported
>> as last active before GPU went to sleep, meaning both requested and active
>> frequencies could end up being reported at their maximum values for the
>> duration of the GPU idle state, it became much more obvious that this does
>> not make sense.
>>
>> To fix this we will now sample the frequency counters only when the GPU is
>> awake. As a consequence reported frequencies could be reported as below
>> the GPU reported minimum but that should be much less confusing that the
>> current situation.
>>
>> v2:
>>   * Split out early exit conditions for readability. (Chris)
>>
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
> 
> I'm happy if you are happy...

Okay pushed, thanks!

Regards,

Tvrtko