On 15/09/2020 23:13, Matthias Kaehlcke wrote: > On Tue, Sep 15, 2020 at 10:55:52PM +0200, Daniel Lezcano wrote: >> On 15/09/2020 19:58, Matthias Kaehlcke wrote: >>> On Tue, Sep 15, 2020 at 07:50:10PM +0200, Daniel Lezcano wrote: >>>> On 15/09/2020 19:24, Matthias Kaehlcke wrote: >>>>> +Thermal folks >>>>> >>>>> Hi Rajendra, >>>>> >>>>> On Tue, Sep 15, 2020 at 11:14:00AM +0530, Rajendra Nayak wrote: >>>>>> 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? >> >> Well, if a SoC vendor decides to mix the units, then there is nothing we >> can do. >> >> When specifying the power numbers available for the SoC, they could be >> all scaled against the highest power number. > > The GPU was just one example, a device could have heat dissipating components > that are not from the SoC vendor (e.g. WiFi, modem, backlight), and depending > on the design it might not make sense to have separate thermal zones. Is it possible to elaborate, I'm not sure to get the point ? >> There are so many factors on the hardware, the firmware, the kernel and >> the userspace sides having an impact on the energy efficiency, I don't >> understand why SoC vendors are so shy to share the power numbers... > > nor do I, someone could just perform measurements to determine DPCs > with the proper scale if Qualcomm refuses to provide them ... > -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog
