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I'm running into a problem specifically with Ubuntu 20.10 and derivatives where the cpu clock is fixed at 800MHz for all cores. This happens with a fresh install of Ubuntu, Kubuntu or POP_OS! 20.10.

However when I install Ubuntu 20.04 all works well- until I upgrade to 20.10. After upgrading the CPU is stuck again.

My laptop is a Dell Precision 7530, the CPU is i9-8950HK. There is a thread (Ubuntu is very slow when Intel SpeedStep is enabled (CPU is not used in full speed)) that suggests a power adapter problem which causes the BIOS to limit CPU scaling. I can't find any evidence that this is the problem I'm experiencing- the file /sys/devices/system/cpu/cpu*/cpufreq/bios_limit does not exist on my system.

Here's the output for cpu0 on Ubuntu 20.10- compared to my current 20.04 system I did not see any differences, except of course a higher frequency:

analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 4294.55 ms.
  hardware limits: 800 MHz - 4.80 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 800 MHz and 4.80 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 800 MHz.

In addition I'd like to not that I dual boot this machine with Windows 10 on a different drive, and I didn't experience any problems with Windows performance. But maybe Windows sets some weird flags that cause these problems in Ubuntu? During all my tests with Ubuntu I did not boot into Windows- in case that's important.

Do you have any advice how to further debug this problem and to get to the root of it?

Thanks!

Update 14.01.2021

I just found out the this clock speed issue does not occur in Ubuntu 21.04 beta, it is something specific to Ubuntu 20.10 and derivatives. That does unfortunately not tell me what the exact problem is, but at least it shows me a working path forward waiting on the next release.

Torsten
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  • Does it stay at this speed under heavy load? What do the temps look like? – rtaft Jan 13 '21 at 20:21
  • @rtaft Yes, all cores stay very close to 800MHz (a few Hz below or above) event under heavy load. Can you please specify which logs I should look at? – Torsten Jan 13 '21 at 20:38
  • I have a very similar cpu (i9 9900k) with scaling seemingly working in 20.10. I suspect the governor is at fault or possibly a bad interaction with a bios setting. Do you have cpupower-gui installed? It might install what you need as dependencies and let you change the governor on all cpus. – N8tron Jan 13 '21 at 23:13
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    @N8tron I did install cpupower-gui. While it allowed me to change the frequencies in the gui, I did not see any effect in the real system. But I found out that the problem is resolved in the current Ubuntu 21.04 beta, so I'm just sitting this one out I guess. – Torsten Jan 14 '21 at 18:38
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    Just adding that I have the same problem. Searched internet, tried various suggested fixes, like adding 'intel_pstate=disable' to grub line, also I used cpupower-gui, but nothing helps at all. I also have dual boot, on windows the processor does increase frequency on heavy load. – user114676 Jan 14 '21 at 19:13
  • Following your suggestion that it works in 21.04 beta, I tried that version out (from USB-stick, not really installed.)

    Indeed, when I then ran 'stress-ng' I could hear the fan starting to blow faster, but then all of a sudden my PC turned itself off. So, that isn't a very good solution for me either.

     – user114676 Jan 14 '21 at 21:13
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    installing new kernel (5.9.16) did not change anything either. I really hope someone can help here, it is really a big problem that I cannot use my PC to its full power! – user114676 Jan 15 '21 at 07:10
  • @user114676 Here's a nice command I found on askubuntu.com that you can use to monitor your cpu frequency on a system where you don't want/can install new software: watch -n1 "cat /proc/cpuinfo | grep MHz". I'm not sure if the switching off of your machine is due to using an early beta? – Torsten Jan 15 '21 at 07:17
  • I just tried the ubuntu 20.04 version on USB, and that works. I think I will downgrade my ubuntu. – user114676 Jan 15 '21 at 15:36
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    I have this same issue. It's astounding that a bug of this magnitude can exist with little to no traction for a fix. – pocket-full-of-quarters Feb 25 '21 at 01:02

2 Answers2

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I think this will probably be solved by removing thermald.

See also here: https://www.reddit.com/r/archlinux/comments/b66d3k/why_was_thermald_removed_from_the_repos/ In that thread someone also mentions a PC being stuck at low frequency because of thermald.

I downgraded to ubuntu 20.04 because of this problem, but recently (perhaps after a thermald upgrade, or a kernel upgrade), I got into new problems: now my PC shuts itself off on heavy load. So after some more research, I decided that it was safe to remove thermald and that problem is now solved.

I don't feel like trying to upgrade to ubuntu 20.10 again, but anyone stumbling on this problem could give removing thermald a try.

user114676
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  • Thank you! That solved the problem for me! I was using Pop OS 20.04 which worked fine until a few weeks ago, when one of their updates seemingly brought in changes from 20.10. Disabling thermald fixed the problem I had till now on Pop OS 20.04. I'm still a bit worried disabling this service, but on the other hand I don't see any negative side effects yet. The fans kick in (Dell Precision 7530, i9) as they should and the performance seems to be as it was when all was working well. Thanks for posting the link to this thread here! – Torsten May 27 '21 at 16:56
  • I've been struggling all day with this problem. Even had to reinstall ubuntu (upgrading from 20.04 to 21.04) nothing worked until I removed thermald and rebooted. Thanks! – nick maxwell May 29 '21 at 03:12
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What solved it for me on 20.04 was adding intel_pstate=active to grub. I've read somewhere that that, even tho it was previously active, it was in pasive mode.

metalinspired
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