Question 258V CPU randomly throttled to 400MHz on Linux 6.14.4 ?

[yikerman]

I'm on an ASUS Zenbook S 14 (UX5406SA, with Intel Core Ultra 7 258V). Normally my CPU's thermal profile is as follows:

$ cpupower frequency-info
analyzing CPU 4:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 4
  CPUs which need to have their frequency coordinated by software: 4
  energy performance preference: balance_power
  hardware limits: 400 MHz - 3.70 GHz
  available cpufreq governors: performance powersave
  current policy: frequency should be within 400 MHz and 3.70 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency: 1.90 GHz (asserted by call to kernel)
  boost state support:
    Supported: yes
    Active: yes

However quite randomly, it will be throttled to only 400MHz:

$ cpupower frequency-info
analyzing CPU 6:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 6
  CPUs which need to have their frequency coordinated by software: 6
  energy performance preference: balance_power
  hardware limits: 400 MHz - 3.70 GHz
  available cpufreq governors: performance powersave
  current policy: frequency should be within 400 MHz and 400 MHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency: 400 MHz (asserted by call to kernel)
  boost state support:
    Supported: yes
    Active: yes

Note that the energy performance preference: balance_power is untouched. I am using tuned & tuned-ppd that is shipped with KDE and never touched its config.

I've read about BD_PROCHOT. However both before and after the bug, sudo rdmsr 0x1FC reports e4005b; plus the issue does not exist in Windows on the same laptop. Where should I even start solving this issue? if this is some Linux firmware bug, where should I report it?

 

[Aeacus]

However quite randomly, it will be throttled to only 400MHz:

Well, it says so on the tin;

frequency should be within 400 MHz and 3.70 GHz. The governor "powersave" may decide which speed to use within this range.

So, you could look into the governor settings.

if this is some Linux firmware bug, where should I report it?

On the dedicated forums of your GNU/Linux distro.

You have what? Arch Linux? Since i can't read out distro name when you just say Linux and it's version.
I could just as well say that i too have two Linux distros. One is version 17.10 and another is 20.1 . Good luck on guessing which distros i use.

 

[yikerman]

Since i can't read out distro name when you just say Linux and it's version.

It occurs on both OpenSUSE TW 6.14.4 and Fedora 42 6.14.3. I believe it's a distro-independent issue.

So, you could look into the governor settings.

Changing the governor to perfoemance has no effect on the throttling.

On the dedicated forums of your GNU/Linux distro.

Thanks I'll look into it.

 

[Aeacus]

It occurs on both OpenSUSE TW 6.14.4 and Fedora 42 6.14.3. I believe it's a distro-independent issue.

Could be distro or distro version issue. After all there are plethora of different GNU/Linux distros out there.

FWIW, i'm running Lubuntu 17.10 on my laptop and Linux Mint LTE 20.1 on my USB thumb drive as live bootable distro (for recovery purposes).

Changing the governor to perfoemance has no effect on the throttling.

Changing the plan, yes. But how about the details/settings of the plan itself?

CPU throttle usually happens when temps go high. Since you have laptop, it struggles with thermals.

Thanks I'll look into it.

👍

 

[rustigsmed]

I had this happen on a Windows (work) laptop recently (not the same model) - down to 400mhz mega slow- the solution was to unplug it and replug it.
Could be worth a go before you go down rabbit holes. Best of luck.

 

[yikerman]

I had this happen on a Windows (work) laptop recently (not the same model) - down to 400mhz mega slow- the solution was to unplug it and replug it.

Thanks for the suggestion. I tried all kinds of power profile settings + plug/unplug and didn't work out.