Re: is 'dynamic-power-coefficient' expected to be based on 'real' power measurements?

On Tue, Sep 15, 2020 at 07:50:10PM +0200, Daniel Lezcano wrote:

On 15/09/2020 19:24, Matthias Kaehlcke wrote:

quoted

+Thermal folks

Hi Rajendra,

On Tue, Sep 15, 2020 at 11:14:00AM +0530, Rajendra Nayak wrote:

quoted

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?

Relative values may work for scheduling decisions, but not for thermal
management with the power allocator, at least not when CPU cooling devices
are combined with others that specify their power consumption in absolute
values. Such a configuration should be supported IMO.

The energy model is used in the cpufreq cooling device and if the
sustainable power is consistent with the relative values then there is
no reason it shouldn't work.

Agreed on thermal zones that exclusively use CPUs as cooling devices, but
what when you have mixed zones, with CPUs with their pseudo-unit and e.g. a
GPU that specifies its power in mW?