Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH v6 03/14] PM: Introduce an Energy Model management framework | Date | Mon, 10 Sep 2018 12:40:55 +0200 |
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On Monday, September 10, 2018 12:38:05 PM CEST Quentin Perret wrote: > On Monday 10 Sep 2018 at 11:44:33 (+0200), Rafael J. Wysocki wrote: > > A kerneldoc comment would be useful here IMO. > > OK > > > > +struct em_cap_state { > > > + unsigned long frequency; /* Kilo-hertz */ > > > > I wonder if the "frequency" field here could be changed into something a bit > > more abstract like "level" or similar? > > > > The reason why is because in some cases we may end up with somewhat artificial > > values of "frequency" like when the intel_pstate driver is in use (it uses > > abstract "p-state" values internally and only produces "frequency" numbers for > > the cpufreq core and the way they are derived from the "p-states" is not always > > entirely clean). > > > > The "level" could just be frequency on systems where cpufreq drivers operate on > > frequencies directly or something else on the other systems. > > I see your point (and TBH we start to have same sort of problems on > Arm) but at this stage I would rather keep this field coherent with > what CPUFreq manages, that is, KHz. The only reason for that is because > the thermal subsystem (IPA) will look at this table to apply a max freq > capping on CPUFreq policies, so things need to be aligned. > > I agree that even if the unit of this field wasn't specified we could > still build a system that works just fine. However if things are too > loosely specified, problems are allowed to happen, so they will.
Fair enough.
> Now, if the CPUFreq core is modified to manipulate abstract performance > levels one day, I'll be happy to change the EM framework the same way :-)
I don't think this is going to happen any time soon, though.
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