Hi Lukasz,
On Fri, Oct 25, 2024 at 5:40 PM Lukasz Luba <lukasz.luba@xxxxxxx> wrote:
> On 10/22/24 14:36, Geert Uytterhoeven wrote:
> > On Tue, Oct 8, 2024 at 11:14 AM Geert Uytterhoeven
> > <geert+renesas@xxxxxxxxx> wrote:
> >> When CONFIG_ENERGY_MODEL=y, an error is printed on RZ/G2E and R-Car E3:
> >>
> >> cpu cpu0: EM: invalid perf. state: -22
> >>
> >> This happens because the Operating Points Parameters tables do not list
> >> voltages, as they are all identical. Previously, it was assumed they
> >> were optional, and unused, when none of the CPU nodes is tied to a
> >> regulator using the "cpu-supply" property. This assumption turned out
> >> to be incorrect, causing the reported error message.
> >>
> >> This RFC patch series fixes this by adding the missing voltages.
> >>
> >> Note that the Energy Model calculates energy efficiency by dividing the
> >> (estimated) CPU power consumption by CPU core clock frequency. When all
> >> voltages have the same value, the former is proportional to clock
> >> frequency, and energy efficiency becomes a constant. Hence all
> >> operating points are considered to have the same efficiency, and the
> >> Energy Model always picks the one with the highest clock rate (see also
> >> [1]).
> >>
> >> Alternatively, the Energy Model could be changed to silently ignore OPP
> >> tables with missing frequencies. IMHO this is not an unusual case.
> >>
> >> Which approach should be taken?
> >> Thanks for your comments!
> >
> > Any comments from the Energy Model and PM people?
>
> My apologies for delay.
>
> So you had issue with bogus Voltage values and removed them.
>
> There is another way to setup EM properly, via DT:
> "opp-microwatt" [1].
>
> That micro watt value won't confuse other subsystems, like
> your regulator fwk. It will only be used by the EM fwk.
>
> This would be an alternative to your voltage values.
> Sounds better to you?
For opp-microwatt, I do need to know the actual power consumption
of the core, right?
Full system power consumption while running the in-kernel
Dhrystones benchmark:
800 MHz: avg 4972,55 mW, stdef 20,474 mW
1000 MHz: avg 5025,93 mW, stdef 18,644 mW
1200 MHz: avg 5059,63 mW, stdef 15,425 mW
The system also has test points across a 0.005 Ohm sense resistor in
the DVFS power supply line, but no on-board measurement sensor (like
the MAX9611 on Salvator-X(S)), so I haven't measured anything
there yet.
> Do you know from /sys/kernel/debug/energy_model/
> the current power values?
With this series applied:
root@ebisu:~# grep -r . /sys/kernel/debug/energy_model/
/sys/kernel/debug/energy_model/cpu0/ps:1200000/inefficient:0
/sys/kernel/debug/energy_model/cpu0/ps:1200000/performance:1024
/sys/kernel/debug/energy_model/cpu0/ps:1200000/cost:3443
/sys/kernel/debug/energy_model/cpu0/ps:1200000/power:352643
/sys/kernel/debug/energy_model/cpu0/ps:1200000/frequency:1200000
/sys/kernel/debug/energy_model/cpu0/ps:1000000/inefficient:1
/sys/kernel/debug/energy_model/cpu0/ps:1000000/performance:853
/sys/kernel/debug/energy_model/cpu0/ps:1000000/cost:3445
/sys/kernel/debug/energy_model/cpu0/ps:1000000/power:293869
/sys/kernel/debug/energy_model/cpu0/ps:1000000/frequency:1000000
/sys/kernel/debug/energy_model/cpu0/ps:800000/inefficient:1
/sys/kernel/debug/energy_model/cpu0/ps:800000/performance:682
/sys/kernel/debug/energy_model/cpu0/ps:800000/cost:3447
/sys/kernel/debug/energy_model/cpu0/ps:800000/power:235095
/sys/kernel/debug/energy_model/cpu0/ps:800000/frequency:800000
/sys/kernel/debug/energy_model/cpu0/flags:0x3
/sys/kernel/debug/energy_model/cpu0/cpus:0-1
Thanks!
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
