Since some time now I noticed that my AMD CPU doesn’t clock down as low as before on kernel 6.12 and 6.15. On kernel 6.6 it can clock down to 500Mhz but on kernel 6.15 it goes to 1600Mhz something like that, and never under even when trying to force things by switching governors. Anyone notice similar behavior?
It is most likely the recent change to the amd-pstate-epp governor which limits the idle speed to the more energy-efficient lowest non-linear frequency rather than the lowest frequency. I think the change was initially introduced in linux613, but it may have been backported to linux612 due to it being the latest LTS release kernel.
It was mentioned in another thread earlier this year:
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As a TL;DR, the fix is here: Udev rule to lower AMD CPU 'scaling_min_freq' value for kernel 6.13 & up - #10 by megavolt
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Since that thread is now locked, I’m asking here.
What was the rationale for AMD to do this change? Were there stability concerns about it?
@scotty65 provided some links here: AMD idle speed higher with kernel 6.13 than with 6.12 - #2 by scotty65
It seemed to be a performance per watt thing.
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