Messages in this thread | | | Date | Wed, 6 Jun 2018 16:29:51 +0100 | From | Quentin Perret <> | Subject | Re: [RFC PATCH v3 03/10] PM: Introduce an Energy Model management framework |
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On Wednesday 06 Jun 2018 at 17:20:00 (+0200), Juri Lelli wrote: > > > This brings me to another question. Let's say there are multiple users of > > > the Energy Model in the system. Shouldn't the units of frequency and power > > > not standardized, maybe Mhz and mW? > > > The task scheduler doesn't care since it is only interested in power diffs > > > but other user might do. > > > > So the good thing about specifying units is that we can probably assume > > ranges on the values. If the power is in mW, assuming that we're talking > > about a single CPU, it'll probably fit in 16 bits. 65W/core should be > > a reasonable upper-bound ? > > But there are also vendors who might not be happy with disclosing absolute > > values ... These are sometimes considered sensitive and only relative > > numbers are discussed publicly. Now, you can also argue that we already > > have units specified in IPA for ex, and that it doesn't really matter if > > a driver "lies" about the real value, as long as the ratios are correct. > > And I guess that anyone can do measurement on the hardware and get those > > values anyway. So specifying a unit (mW) for the power is probably a > > good idea. > > Mmm, I remember we fought quite a bit while getting capacity-dmpis-mhz > binding accepted, and one of the musts was that the values were going to > be normalized. So, normalized power values again maybe?
Hmmm, that's a very good point ... There should be no problems on the scheduler side -- we're only interested in correct ratios. But I'm not sure on the thermal side ... I will double check that.
Javi, Viresh, Eduardo: any thoughts about this ?
Thanks ! Quentin
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