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Bug#1038981: capping maximum frequency no longer works in kernel 6.1



On Saturday, 24 June 2023 00:19:50 CEST Al Ma wrote:
> Below, I try to cap the frequency for each of my processor cores, but some
> cores resists: ...
> ...
> The governor is powersave everywhere.

If I put "powersave frequency governor" in a search engine, one of the first 
results points to arch wiki, so of course I check that first:
https://wiki.archlinux.org/title/CPU_frequency_scaling#Scaling_governors
which says "powersave 	Run the CPU at the minimum frequency"
which indicates that you're trying to do the exact same thing as the governor 
already does. Why?!? (rhetorical question, don't answer it) ...

> For kernel 5 with Debian 11 (which I can no longer test), everything worked

Reverting back to Debian 11 userland is difficult (and likely irrelevant), but 
trying the 5.10 kernel should still be possible afaik.

> like a charm (or at least I always observed all-400-MHz back then). So
> either the new kernel is erroneous or my processor broke somehow (perhaps,
> during the upgrade). It has Intel(R) Core(TM) i7-10610U CPU @ 1.80GHz. 

... That same wiki page has a purple box saying:
"Note: Each governor is compatible with any scaling driver, with the 
exceptions of intel_pstate and amd_pstate in active mode, which provide 
pseudo-governors in the form of powersave and performance. See #Autonomous 
frequency scaling below."

follow that link and you'll see
"Both Intel and AMD define a way to have the CPU decide its own speed"

You have an intel CPU, so I put "Intel p-state" in a search engine and one of 
the first results points to a document on kernel.org. Update version number to 
6.1: https://www.kernel.org/doc/html/v6.1/admin-guide/pm/intel_pstate.html

> Who is the culprit? What to do?

I literally put 2 questions in a search engine and the very first link I 
checked from each result (arch wiki + kernel.org) gave me the likely answer or 
enough information to do an actual deep dive.

I don't want to be an ass, but why didn't you do such elementary research 
before filing a bug report?

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