[Bug 219332] /sys/devices/system/cpu/cpufreq/policy0/energy_performance_preference: Device or resource busy

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=219332

Dhananjay Ugwekar (AMD) (Dhananjay.Ugwekar@amd.com) changed:

           What    |Removed                     |Added
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                 CC|                            |Dhananjay.Ugwekar@amd.com

--- Comment #6 from Dhananjay Ugwekar (AMD) (Dhananjay.Ugwekar@amd.com) ---
(In reply to Artem S. Tashkinov from comment #0)
> Created attachment 306935 [details]
> A dump of /sys/devices/system/cpu
> 
> I've played with various tee: /sys/devices/system/cpu/cpufreq/policy0/*
> options and now on Linux 6.11 and Ryzen 7 5800X I'm getting this:
> 
> perfbias.sh power
> Now: performance
> Switching to: power
> tee: /sys/devices/system/cpu/cpufreq/policy0/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy10/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy11/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy12/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy13/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy14/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy15/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy1/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy2/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy3/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy4/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy5/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy6/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy7/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy8/energy_performance_preference:
> Device or resource busy
> tee: /sys/devices/system/cpu/cpufreq/policy9/energy_performance_preference:
> Device or resource busy
> Result: performance
> 
> This doesn't seem right.

I see from the attachment that you are using performance governor, so you are
limited to only performance EPP hint, trying to write other EPP hints
(power/balance_power/balance_performance) will show the above error. 

You'll need to change to powersave governor to use these hints. Please let me
know if this fixes your issue.

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