OLIMEX / OLIMEX/olimage

Lime A64 runs all cores on max frequency

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Dominant language
Python
Stars
17
Forks
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Description

Hi, I noticed my A64 was getting quite warm. I found that it was running all cores at maximum frequency all the time.

Using cpufreq-info I found that its performance was mediated by the "performance" governor.

I debugged the issue and found that in the cpufrequtils service less /etc/init.d/cpufrequtils is started. This script tries to start the CPU by default with the "ondemand" governor. Unfortunately this governor is NOT available for the A64. Therefore it starts with the performance governor.

Solution is to create /etc/default/cpufrequtils with contents GOVERNOR=schedutil to set the governor to schedutil. This behaves similar to ondemand in that it schales the frequency based on the process scheduler (although ondemand is somewhat more aggressive).

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Research direction

Start with the cpufrequtils service and its default configuration at /etc/default/cpufrequtils. Check the available CPU-frequency governors with cpufreq-info and verify how the service selects a governor when the default is unavailable. Done means the A64 boots with a scheduler-based governor instead of performance and the relevant configuration or documentation reflects that behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
linux
Domain
operating-systems, performance
Issue type
Bug
Difficulty
1/5
Estimated time
Under an hour
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
48/100

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