Hi Rob,
There has been some discussions on another thread [1] around the DPC (dynamic-power-coefficient) values
for CPU's being relative vs absolute (based on real power) and should they be used to derive 'real' power
at various OPPs in order to calculate things like 'sustainable-power' for thermal zones.
I believe relative values work perfectly fine for scheduling decisions, but with others using this for
calculating power values in mW, is there a need to document the property as something that *has* to be
based on real power measurements?
Looking at the bindings,
dynamic-power-coefficient:
$ref: '/schemas/types.yaml#/definitions/uint32'
description:
A u32 value that represents the running time dynamic
power coefficient in units of uW/MHz/V^2. The
coefficient can either be calculated from power
measurements or derived by analysis.
The dynamic power consumption of the CPU is
proportional to the square of the Voltage (V) and
the clock frequency (f). The coefficient is used to
calculate the dynamic power as below -
Pdyn = dynamic-power-coefficient * V^2 * f
where voltage is in V, frequency is in MHz.
.. the 'can either be calculated from power measurements or derived by analysis'
tells me we don't mandate that this be based on real power measurements.
If we do, then perhaps that needs to be mentioned explicitly?
thanks,
Rajendra
[1] https://lore.kernel.org/patchwork/patch/1287119/#1494073
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