Amd_pstate - latest kernels ( 6.15 or more ) and Zen2

[GaVenga]

(CPU: AMD Ryzen 7 3700X 8-Core Processor)

Since kernel 6.15 or maybe earlier:
the grub-parameter amd_pstate.shared_mem=1 amd_pstate=active
is needed for clocking down to minimal frequency.
amd_pstate=passive does not change any think (checked with cpu-x)

New driver amd_pstate-epp used by newer kernels afaik…

[stephane]

there many changes on amd-pstate on end 6.14.9 kernel and new series 6.15
can you use : amd-pstate ( no more amd_pstate.share_mem=1 )
UEFI up to date for your UEFI motherboard version
CPPC active

you can without option , you should see
amd-pstate-epp , with scheduler powersave_perfomance

if you try with
amd-pstate=active or passive or guided, you will see older scheduler ( schedutil , balance , perfomance and powersave )

check all cases with

cpupower frequency-info
sudo lscpu -ae

see changes on amd-pstate
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/drivers/cpufreq

documentation
https://www.kernel.org/doc/html/latest/admin-guide/pm/amd-pstate.html#kernel-module-options-for-amd-pstate

see also this topic i you really want lower frequency

AMD idle speed higher with kernel 6.13 than with 6.12

After the Feb 4 testing branch update, which went just fine across the board, I also tried out the 6.13.1-2 kernel update. On my antique Intel laptop there are no issues. On both my AMD machines, (Zen3 desktop and Zen4 laptop), both using tuned 2.25.1-1 (balanced power profile) for power management, the CPU idle speed jumps under 6.13 as compared to 6.12 with no other changes–simply making the appropriate choice in the grub menu. On the desktop, idle speed jumps from 550 MHz to 1737 MHz. The…

[robin0800]

[the solution is in here]
(Udev rule to lower AMD CPU 'scaling_min_freq' value for kernel 6.13 & up)

I had to alter the min frequency for my CPU

[GaVenga]

@stephane

you can without option , you should see
amd-pstate-epp , with scheduler powersave_perfomance

and without amd_pstate
(or amd_pstate.shared_mem=1 amd_pstate=active
or amd_pstate.shared_mem=1 amd_pstate=passive)

==> kernels up from 6.12 (LTS) detect cpu without any GRUB-parameter
and load amd-pstate-epp auto-magicly…

On older LTS-kernels Grub-Parameters are necessary.
I had 5.15 LTS for example, loads acpi-freq whatever I try (normal behavior) .

[omano]

Are you sure that is you set amd_pstate=active it doesn’t enable the new amd_pstate_epp? Because it does here. I need it to be passive to get the classic amd_pstate.

[GaVenga]

@omano

Are you sur

Sure that:
amd_pstate=active DOES enable amd_pstate_epp
even without Grub-Parameter “amd_pstate=active”…

[stephane]

and this
amd-pstate=active ?

[omano]

I meant, if you set amd_pstate=active, you end up with amd_pstate_epp.
You need amd_pstate=passive if you want amd_pstate.

@GaVenga

Sure that:
amd_pstate=active DOES enable amd_pstate_epp

Yes, that’s my point, and not what I understand you wrote previously.