Do not set any Turbo boost flags when using amd_pstate_epp driver

[LDprg]

Description

I have been using auto-cpufreq for quite a while and have been recently investigating into using it with amd_pstate_epp. Everything has been working great except for a error spam of the service. Since everything except turbo boost is working fine I did some investigations.

It seems like amd_pstate_epp is managing its turbo boost in the driver it self and not exposing the /sys/devices/system/cpu/cpufreq/boost flag. This probaply results in auto-cpufreq setting this flag and causing alot of error spam (see below).

Another thing is that intel pstate could also have the same error (see #661).

Also #602 seems related to this.

A simple solution (if my assumptions are correct) would be to just not touch any boost related flags like /sys/devices/system/cpu/cpufreq/boost.

Feel free to correct my if I am wrong.

Edit:
I did some benchmarking using the sysbench cpu benchmark. I get on my system better peformance using amd-pstate-epp than amd-pstate and cpi-cpufreq driver.

Error output:

cpufreqctl.auto-cpufreq: line 105: echo: write error: Device or resource busy

---

System information:

-------------------------------------------------------------------------------

Linux distro: NixOS 24.05 Uakari
Linux kernel: 6.8.1
Processor: AMD Ryzen 7 5800H with Radeon Graphics
Cores: 16
Architecture: x86_64
Driver: amd-pstate-epp

------------------------------ Current CPU stats ------------------------------

CPU max frequency: 4463 MHz
CPU min frequency: 400 MHz

Core	Usage	Temperature	Frequency
CPU0      1.0%        52 °C       400 MHz
CPU1      0.0%        52 °C      3572 MHz
CPU2      1.0%        52 °C       400 MHz
CPU3      0.0%        52 °C      3333 MHz
CPU4      2.0%        52 °C      4330 MHz
CPU5      4.0%        52 °C       400 MHz
CPU6      2.0%        52 °C       400 MHz
CPU7      1.0%        52 °C       400 MHz
CPU8      1.0%        52 °C       400 MHz
CPU9      3.0%        52 °C       400 MHz
CPU10      0.0%        52 °C       400 MHz
CPU11      0.0%        52 °C       400 MHz
CPU12      1.0%        52 °C       400 MHz
CPU13      1.0%        52 °C      3303 MHz
CPU14      1.0%        52 °C      3140 MHz
CPU15      0.0%        52 °C      3431 MHz

CPU fan speed: 0 RPM

auto-cpufreq version: 1.9.9
Git commit: v1.9.9

Python: 3.11.8
psutil package: 5.9.8
platform package: 1.0.8
click package: 8.1.7
distro package: 1.9.0

Computer type: Notebook
Battery is: charging

auto-cpufreq system resource consumption:
cpu usage: 0.0 %
memory use: 0.07 %

Total CPU usage: 1.7 %
Total system load: 0.37
Average temp. of all cores: 52.00 °C 

Currently using: performance governor
Warning: CPU turbo is not available
Currently turbo boost is: off

-------------------------------------------------------------------------------

[LDprg]

Another thing is also going on (maybe related) the EPP does not contain the value I specified in the config. Seems like my config is just ignored.

Also the error in the log file does not seem to relate to turbo boost. I seems setting EPP per core doesn't work correctly.
This command results in the same error:

> echo "power" | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/energy_performance_preference
power
tee: /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu1/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu2/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu3/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu4/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu5/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu6/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu7/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu8/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu9/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu10/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu11/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu12/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu13/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu14/cpufreq/energy_performance_preference: Device or resource busy
tee: /sys/devices/system/cpu/cpu15/cpufreq/energy_performance_preference: Device or resource busy

[LDprg]

This might also be relevant. On my system the governor mode effects which epp can be selected.

[LDprg]

Updated my auto-cpufreq to 2.2.0 (using nixos flake now) and most stuff is gone.