Latest Stable kernels - amd-pstate-epp idle frequencies faster

ArchyLife · 2025-12-17 07:24:16

Hi,

I've noticed on LTS running a Ryzen 5 5600X, my idle frequency in the past was 550mhz.

On the latest Stable kernels I've been noticing it now idles at 1738mhz.

I'm not sure if this is now the normal behavior with the latest Stable, or it will be changed at some point..

But for now I'm wondering if we now need to adjust/set a power profile manually to get the older behaviour in LTS with lower frequencies, if it's now always going to be this way?

I haven't touched anything on my system, so it's running the default amd-pstate-epp active mode.

THANKS

Last edited by ArchyLife (2025-12-17 07:24:52)

jl2 · 2025-12-17 09:26:26

I don't know if this is related, I have a 5900x with the no_hz=2-23 for tickless idles on these threads.
On these threads, cpufreq reports something around the 1.7 GHz, and never changes them, so it might just be reporting?

Does the LTS already have the active mode? I don't remember when it was introduced, but I also remember the reported minimum frequency got quite a bump up.

Is the power draw actually higher on idle? You can read it with tools like turbostat (run with sudo)

BS86 · 2025-12-17 12:42:21

on modern CPU's, powerstates are not hard linked to frequencies.
to put it in a understandable, not to technical way, acpi cpufreq just couldn't handle the powerstates right, pstate now does and the powerstate is actually at it's lowest although the frequency appears rather high.

I read an email on the LKML for a pull request that actually set the idle frequency higher that had some details with powerdraw compared to powerstates that showed that frequency does not matter at all as long as the powerstate is at it's lowest which the pstate driver does, but I can't find that exaxt mail now.
This however is the change that you seem to notice now with switching kernels:
https://lkml.org/lkml/2024/10/3/364

Last edited by BS86 (2025-12-17 12:51:44)

ArchyLife · 2025-12-18 00:31:06

HI,

@jl2 The last LTS I used 6.12.x it was Active Mode... I can't say I've noticed a Power Draw difference.

@BS86 The information I read online is that the powerstate for amd-pstate-epp is suppose to be 500mhz and that on the latest Stable, it's not at it's lowest..

But according to the patch, if we are now setting to lowest_nonlinear_freq instead of lowest_freq, maybe then the idle of 1738mhz is correct now... hmm

THANKS

Last edited by ArchyLife (2025-12-18 00:31:36)

ArchyLife · 2026-01-17 01:40:50

Anyone know the facts here, is this now how the behaviour is suppose to be in the latest kernels or it's an issue that has yet to be corrected?

Because I thought as I mentioned that 500mhz idle is suppose to be correct, and I'm still trying to figure this out.

THANKS

Last edited by ArchyLife (2026-01-17 01:41:19)

jl2 · 2026-01-17 07:13:23

@jl2 The last LTS I used 6.12.x it was Active Mode... I can't say I've noticed a Power Draw difference.

My guess is they are just being reported wrong. Try comparing the before/after and check if there's a difference.

Arch Linux

#1 2025-12-17 07:24:16

Latest Stable kernels - amd-pstate-epp idle frequencies faster

#2 2025-12-17 09:26:26

Re: Latest Stable kernels - amd-pstate-epp idle frequencies faster

#3 2025-12-17 12:42:21

Re: Latest Stable kernels - amd-pstate-epp idle frequencies faster

#4 2025-12-18 00:31:06

Re: Latest Stable kernels - amd-pstate-epp idle frequencies faster

#5 2026-01-17 01:40:50

Re: Latest Stable kernels - amd-pstate-epp idle frequencies faster

#6 2026-01-17 07:13:23

Re: Latest Stable kernels - amd-pstate-epp idle frequencies faster

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