Ubuntu CPU – Frequency Drops Under Load Without Thermal Issues

cpucpu-frequencyintelUbuntu

This problem is bothering me for some weeks now and I cannot seem to figure out what the real problem might be.

The problem is that the CPU frequency is dropping drastically when under load. By this I mean that the CPU frequency is around 400 MHz when just opening a web browser for example, and when there is no load the frequency is rising back up. (not to a very high one, but still it is not a static behavior). It is really driving me crazy.

Some further information that might help:

Hardware:

Lenovo thinkpad T15:

CPU: Intel I7-10510U

=> Base clock: 1.8GHz

=> Boost clock: 4.9GHz

Software:

Distro: Ubuntu 20.04.1 LTS

Kernel: 5.4.0-52-generic

⇒  cpupower frequency-info
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:  Cannot determine or is not supported.
  hardware limits: 400 MHz - 4.90 GHz
  available cpufreq governors: performance powersave
  current policy: frequency should be within 400 MHz and 4.90 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency: Unable to call hardware
  current CPU frequency: 1.24 GHz (asserted by call to kernel)
  boost state support:
    Supported: yes
    Active: yes

# command to simulate a stress on the CPU
⇒  stress-ng --cpu 8 --timeout 15s
stress-ng: info:  [43652] dispatching hogs: 8 cpu
stress-ng: info:  [43652] successful run completed in 15.34s

# The result of the stress on the CPU
⇒  sudo turbostat --Summary --quiet  --show Busy%,Bzy_MHz,PkgTmp,PkgWatt,GFXWatt,IRQ --interval 6
Busy%   Bzy_MHz IRQ PkgTmp  PkgWatt GFXWatt
6.58    1862    11418   51  5.00    0.00
7.69    1813    14444   51  4.96    0.00
7.79    1817    16988   51  5.03    0.00
7.99    1724    14679   51  5.00    0.00
9.12    1542    14504   51  4.91    0.00
8.82    1662    13878   51  4.98    0.00
60.61   1060    19508   52  5.84    0.00 # Applied load around here
99.75   460     19984   51  4.59    0.00
98.06   654     21316   51  4.79    0.00
10.26   1181    16730   51  4.25    0.00 # load ended around here
5.90    1782    10315   50  4.74    0.00
6.60    1890    11701   50  5.10    0.00
6.00    1901    10736   50  5.13    0.00
6.74    1981    13477   51  5.23    0.00
7.43    1731    1500    50  4.92    0.00

⇒  cpufreq-info
cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to cpufreq@vger.kernel.org, please.
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: 400 MHz - 4.90 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 400 MHz and 4.90 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 1.26 GHz.
analyzing CPU 1:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 1
  CPUs which need to have their frequency coordinated by software: 1
  maximum transition latency: 4294.55 ms.
  hardware limits: 400 MHz - 4.90 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 400 MHz and 4.90 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 1.48 GHz.
analyzing CPU 2:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 2
  CPUs which need to have their frequency coordinated by software: 2
  maximum transition latency: 4294.55 ms.
  hardware limits: 400 MHz - 4.90 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 400 MHz and 4.90 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 982 MHz.
analyzing CPU 3:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 3
  CPUs which need to have their frequency coordinated by software: 3
  maximum transition latency: 4294.55 ms.
  hardware limits: 400 MHz - 4.90 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 400 MHz and 4.90 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 983 MHz.
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
  maximum transition latency: 4294.55 ms.
  hardware limits: 400 MHz - 4.90 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 400 MHz and 4.90 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 1.06 GHz.
analyzing CPU 5:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 5
  CPUs which need to have their frequency coordinated by software: 5
  maximum transition latency: 4294.55 ms.
  hardware limits: 400 MHz - 4.90 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 400 MHz and 4.90 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 872 MHz.
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
  maximum transition latency: 4294.55 ms.
  hardware limits: 400 MHz - 4.90 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 400 MHz and 4.90 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 926 MHz.
analyzing CPU 7:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 7
  CPUs which need to have their frequency coordinated by software: 7
  maximum transition latency: 4294.55 ms.
  hardware limits: 400 MHz - 4.90 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 400 MHz and 4.90 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 850 MHz.

Things I've tried so far:

setting power governor to performance
setting the intel pstate driver frequency limits
using cpupower to set the frequency limits (Does this the same as changing the intel pstate driver values directly?)
Reinstalling ubuntu 20.04, had the same issue upon a clean install.

I was able once to get my system up and running like it should be: After rebooting from windows, the CPU went right up to the max CPU limit when running a fake load onto the system and kept working for the rest of the day. The system thermal throttled as expected, but never dropped below the 2 GHz as far as I could tell. However after rebooting the issue reappeared… I wasn't able to reproduce this behavior afterwards either…

If it was not clear already: the question is how to solve this so that I can use the full potential of my laptop and not wait every time I load a new window or open a new browser tab?

Thanks in advance!

EDIT:

add reinstall to things I tried

Best Answer

Probably your embedded controller is set to a conservative thermal setting. Note that these settings are persistent on the mainboard and not the hard disk. So if you are playing with Lenovos tools under windows, putting your notebook in a kind of "power economic & quiet" profile and then boot up ubuntu, the setting is still active.

To change this under Ubuntu, you need the right kernel module (in my case it's dell-smbios) and the smbios-thermal-ctl package to do something like this:

sudo smbios-thermal-ctl -i

 Print all the Available Thermal Information of your system: 
-------------------------------------------------------------------
Supported Thermal Modes: 
     Balanced
     Cool Bottom
     Quiet
     Performance

and then activate a more permissive profile, in my case (Dell) the best of both worlds seems to be Balanced.

sudo smbios-thermal-ctl --set-thermal-mode=Balanced

Another tool I can recommend is s-tui to diagnose such behavior.

Related Solutions

Linux – How to add CPU frequency governors to the Linux kernel

You'll have to find the code for that specific governor and add it to your kernel before recompiling it or you can also write the proper Makefile and compile the governor as a module. The code for the governor should be in drivers/cpufreq/. For example, for the lulzactive governor: drivers/cpufreq/cpufreq_lulzactive.c

Is it possible to set a constant lowest CPU frequency under the modern PSTATE driver

Well, well, turns out that the new pstate Intel driver is awesome, but first one needs to practice a bit of the ancient, lost art of reading the documentation.

I'll leave my question as it is because, judging by all the grief and frustration I see scattered all around the internet, I am not the first to have this issues.

The new CPU driver has lots of options, but I will restrict my explanation to something simple and, for me, more than enough and satisfactory. First of all:

sudo apt-get install linux-cpupower

(or the equivalent in your non-debian based distros)

There are now 2 behaviors (governors) with the names powersave and performance but that is quite an unfortunate naming scheme, because these governors have nothing to do with those that bear the same names in the old driver:

powersave means now variable frequency that depends on the load, i.e. this is essentially the old ondemand governor. You get to set the minimum and maximum frequency, and if that maximum frequency is set to the maximum frequency your CPU is able of (which I believe it's the default) then you don't save a crap. You may even crank up the minimum frequency to the second highest value, and the result will be the CPU nearly at full throttle 24/7 and the governor will still be named powersave. They should have named this governor VARIABLE or something similar, avoiding a lot of confusion among users and sparing the developers a lot of false reports of kernel bugs.
performance means here constant frequency, no matter the load, and this depends on what the user has set as maximum. When this governor is set, the mininum frequency is ignored and the CPU runs at the frequency you set as maximum. If as such you have set a very low frequency, then you will not see any special performance or anything, you just will get a slowed down CPU at constant frequency. So they'd better named this governor CONSTANT or something similar, sparing frustration to many people like me, used to the old scheme.

So, here are some examples that work like a charm, at least with kernel 4.14. I will use as minimum and maximum frequency the values for my CPU: 0.4 and 3.1 GHz. See yours with cpupower frequency-info

CONSTANT, LOWEST FREQUENCY IN ALL CORES

This IS what I wanted! We get that by setting the constant frequency governor and setting the lowest available frequency as the maximum:

sudo cpupower frequency-set -g performance
sudo cpupower frequency-set -u 400MHz

CONSTANT, HIGHEST FREQUENCY IN ALL CORES

(You see this asked very often for desktop computers where it makes sense, although there are also people out there willing to destroy their laptop fan)

sudo cpupower frequency-set -g performance
sudo cpupower frequency-set -u 3100MHz

VARIABLE FREQUENCY BETWEEN THE MINIMUM AND MAXIMUM POSSIBLE FREQUENCIES IN ALL CORES

(this was called ondemand with the old acpi-cpufreq driver)

sudo cpupower frequency-set -g powersave
sudo cpupower frequency-set -d 400MHz
sudo cpupower frequency-set -u 3100MHz

VARIABLE FREQUENCY BETWEEN THE MINIMUM AND A MODERATE FREQUENCY IN ALL CORES

(maybe because you want to get some more speed when required but you don't want to reach the maximum and hear the fan blowing like mad)

sudo cpupower frequency-set -g powersave
sudo cpupower frequency-set -d 400MHz
sudo cpupower frequency-set -u 1200MHz

And so on. It is very easy and works really well. You can set too a constant low frequency in one core where the heavy numerical stuff is running, while you leave a variable frequency in other core where you launch the more usual stuff (email, web browsing...). See taskset for more info.