I have experimented with different gnome extensions to control the performance and battery life on my laptop. Notably, I installed and uninstalled these two extensions:

I partly run them at the same time, then uninstalled and reinstalled them. Now my CPUs are stuck at the minimum frequency and changing the governor has no more effect.

user@XPS:~$ cat /proc/cpuinfo | grep MHz
cpu MHz     : 800.039
cpu MHz     : 800.035
cpu MHz     : 800.037
cpu MHz     : 800.026
cpu MHz     : 800.008
cpu MHz     : 800.036
cpu MHz     : 800.040
cpu MHz     : 800.028

user@XPS:~$ for governor in $(ls /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor); do cat $governor; done

How can I trouble-shoot this?

Here some more information:

The CPUs remain at 800 Mhz even under load. (I tested it running 0.A.D. with six bots on a large map.)

user@XPS:~$ grep . /sys/devices/system/cpu/cpu*/cpufreq/scaling_driver

user@XPS:~$ grep . /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq

user@XPS:~$ grep . /sys/devices/system/cpu/cpu*/cpufreq/scaling_min_freq

user@XPS:~$ grep . /sys/devices/system/cpu/intel_pstate/*perf_pct
  • 1
    Start with what CPU frequency driver? Do grep . /sys/devices/system/cpu/cpu*/cpufreq/scaling_driver. Next, what are the max and mins? Do: grep . /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq and grep . /sys/devices/system/cpu/cpu*/cpufreq/scaling_min_freq and if your driver is intel_pstate: grep . /sys/devices/system/cpu/intel_pstate/*perf_pct. then we'll go from there. Note: I never ever use any of those add on tools. Oh, and if you have no load at all (unlikely in a desktop (O.K. LapTop) with a GUI), you might well see 800 MHz, even in performance mode. – Doug Smythies Jul 2 at 18:46
  • Yes if you give it no work the frequency is low. Try running a computation and rerun your command. – Yvain Jul 2 at 18:54
  • I added the above requested information. Even under heavy load the frequency remains constantly 800 Mhz. – mace Jul 2 at 19:26
  • If your processor is HWP capable, try to disable it. You could also try to disable the intel_pstate driver entirely, witch would then cause the acpi-cpufreq driver to be used. These are all grub GRUB_CMDLINE_LINUX_DEFAULT options, intel_pstate=disable and intel_pstate=passive intel_pstate=no_hwp. I would very much like to understand your issue. – Doug Smythies Jul 2 at 20:11
  • Actually, first try this echo powersave | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor and does that un-stick it? are there any indications of thermal events in any of your log files? – Doug Smythies Jul 2 at 20:17

After checking different options in grub with no result, I booted a clean ubuntu image from USB. The CPU frequency was still at 800 Mhz indication that it wasn't OS related. A quick search yielded that this is a Dell safeguard mechanism to protect the laptop and is triggered by a thermal event, bad battery, or faulty charger. In my case, it was probably a thermal event I had at the same time I experimented with the above-mentioned extensions. My laptop failed to sleep and went full throttle in my rucksack sometime last week.

The solution was to unscrew the back-lid and disconnect the battery for >15 seconds. This resets the safeguard mechanism. After reboot the CPU is again following the intel_pstate settings.

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