[Intel-gfx] [PATCH i-g-t v3 6/9] intel-gpu-overlay: Use RAPL PMU for power reading

[Chris Wilson]

Quoting Tvrtko Ursulin (2017-10-10 13:05:40)
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> Wire up to the RAPL PMU for GPU energy readings.
> 
> The only complication is that we have to add code to parse:
> 
>  # cat /sys/devices/power/events/energy-gpu.scale
>  2.3283064365386962890625e-10
> 
> v2: Link with -lm.
> v3: strtod can handle scientific notation, even though my initial
>     reading of the man page did not spot that. (Chris Wilson)
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris