On 10/28/24 11:34, Geert Uytterhoeven wrote:
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?
Correct. You can try to derived that in a way you did and put below.
Although, Dhrystone is a synthetic micro-benchmark with small
impact to data caches, so it will not use much power.
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
Right. From those power values can be try to derive the
'CPU only power' values - assuming only one core was
running the test.
AFAIU you don't have proper DVFS due to missing voltage scaling.
Therefore...
Out of that I got these CPU power values:
800MHz -> 174mW
1000MHz -> 212mW
1200MHz -> 261mW
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
Those power values listed above look a bit higher, but they
could be more related to a benchmark which utilized caches
and more parts of the CPU. I don't know if you had chance to
see some of my presentations on Linux conferences, where
I show how much power can vary in different scenarios at
the same frequency...
TLDR; it can be even 1.8x comparing to Dhrystone.
So would say it's OK for you to put either your Dhrystone
power results, or these one from EM dump (probably from
some more heavy benchmark then set into DT coefficient
to derive them in OPP fwk).
Your platform AFAIK is not Heterogeneous, so it won't be used
in EAS w/ that EM. It will be only used for thermal governor
IPA or PowerCap DTPM, which require EM to work.
Regards,
Lukasz
