From: Matthias Kaehlcke <mka@chromium.org>
To: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Rajendra Nayak <rnayak@codeaurora.org>,
Lukasz Luba <lukasz.luba@arm.com>,
Rob Herring <robh+dt@kernel.org>,
DTML <devicetree@vger.kernel.org>,
Doug Anderson <dianders@chromium.org>,
linux-pm@vger.kernel.org,
Amit Daniel Kachhap <amit.kachhap@gmail.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Javi Merino <javi.merino@kernel.org>
Subject: Re: is 'dynamic-power-coefficient' expected to be based on 'real' power measurements?
Date: Tue, 15 Sep 2020 10:58:08 -0700 [thread overview]
Message-ID: <20200915175808.GB2771744@google.com> (raw)
In-Reply-To: <406d5d4e-d7d7-8a37-5501-119b734facb3@linaro.org>
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?
next prev parent reply other threads:[~2020-09-15 17:59 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <248bb01e-1746-c84c-78c4-3cf7d2541a70@codeaurora.org>
2020-09-15 17:24 ` is 'dynamic-power-coefficient' expected to be based on 'real' power measurements? Matthias Kaehlcke
2020-09-15 17:50 ` Daniel Lezcano
2020-09-15 17:58 ` Matthias Kaehlcke [this message]
2020-09-15 20:55 ` Daniel Lezcano
2020-09-15 21:13 ` Matthias Kaehlcke
2020-09-15 21:23 ` Daniel Lezcano
2020-09-15 21:36 ` Matthias Kaehlcke
2020-09-16 4:15 ` Rajendra Nayak
2020-09-16 16:40 ` Matthias Kaehlcke
2020-09-15 21:46 ` Doug Anderson
2020-09-15 21:51 ` Matthias Kaehlcke
2020-09-16 9:53 ` Lukasz Luba
2020-09-16 16:48 ` Matthias Kaehlcke
2020-09-24 6:09 ` Rajendra Nayak
2020-09-24 8:21 ` Lukasz Luba
2020-09-16 9:18 ` Lukasz Luba
2020-09-15 19:53 ` Doug Anderson
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