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    SubjectRe: [RFC PATCH v3 03/10] PM: Introduce an Energy Model management framework
    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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