Slimbook-Team/slimbookbattery

"Limit CPU profile" setting doesn't seem to apply

Opened this issue · 2 comments

byteManiak commented

Describe the bug
When switching from "none" to "maximum" in "Limit CPU profile", /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference should be set to power, but it's still set to performance

To Reproduce

  1. Set "Limit CPU profile" to "none".
  2. Set "Limit CPU profile" back to "maximum".

Desktop (please complete the following information):

  • OS: Arch Linux
  • Version: latest Linux kernel as of the ticket (kernel 6.4.1)
  • Desktop Environment: KDE Plasma
  • CPU: Ryzen 6850U
  • Power driver: amd-pstate-epp

Additional context
I manually set energy_performance_preference to power:

[root@Lenny policy0]# echo power > energy_performance_preference 
[root@Lenny policy0]# cat energy_performance_preference 
power

Then I set the Slimbook Battery profile to Maximum performance, which also changes "Limit CPU profile" to "none". This sets energy_performance_preference to performance, as expected. I also can't write power to this while Maximum performance is enabled:

[root@Lenny policy0]# echo power > energy_performance_preference 
bash: echo: write error: Device or resource busy

Then I set the Slimbook Battery profile back to Energy Saving, which changes "Limit CPU profile" back to "maximum". This should set energy_performance_preference to power, but it doesn't:

[root@Lenny policy0]# cat energy_performance_preference 
performance

I can manually set the setting to power just fine though:

[root@Lenny policy0]# echo power > energy_performance_preference 
[root@Lenny policy0]# cat energy_performance_preference 
power

I'm not too sure if this is a Slimbook Battery bug, or if it's something in TLP.

siddhpant commented

Might be related to linrunner/TLP#630.

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utrack commented

It's definitely related to the TLP issue; the EPP mechanism is new.
EPP is set to performance automatically by the EPP driver when the CPU policy is set to performance (which is why you can't write anything there); however, it does not pin 'power' to powersave or any other CPU policies.

So in short, EPP is not supported yet by TLP or sbb at all, the 'performance' EPP switch is a side effect of the CPU driver.

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