WarrenFaith's questions

I have a Lenovo T570 with Xubuntu 18.04 LTS. My current issue is that my cpu speed stepping is kind of going nuts and does what ever it thinks its best.

Sample: when I run my IDE and cpu load increases during build time, the governor changes automatically. I caught the moment during compiling my project with the following call:

martin@martin-ThinkPad-T570:~$ while cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor; do sleep 1; done
powersave
powersave
performance
performance

cpufreq-info tells me this:

martin@martin-ThinkPad-T570:~$ cpufreq-info 
cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to [email protected], 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 - 3.50 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 3.50 GHz and 3.50 GHz.
                  The governor "performance" may decide which speed to use
                  within this range.
  current CPU frequency is 3.25 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 - 3.50 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 3.50 GHz and 3.50 GHz.
                  The governor "performance" may decide which speed to use
                  within this range.
  current CPU frequency is 3.36 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 - 3.50 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 3.50 GHz and 3.50 GHz.
                  The governor "performance" may decide which speed to use
                  within this range.
  current CPU frequency is 3.26 GHz.
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 - 3.50 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 3.50 GHz and 3.50 GHz.
                  The governor "performance" may decide which speed to use
                  within this range.
  current CPU frequency is 3.36 GHz.

Please take a look at

current policy: frequency should be within 3.50 GHz and 3.50 GHz. The governor "performance" may decide which speed to use

Afterwards to go back to powersave I use my little script:

martin@martin-ThinkPad-T570:~$ cat cpu_freq_save.sh 
#!/bin/bash
sudo cpufreq-set -g powersave -c 0 --min 400MHz
sudo cpufreq-set -g powersave -c 1 --min 400MHz
sudo cpufreq-set -g powersave -c 2 --min 400MHz
sudo cpufreq-set -g powersave -c 3 --min 400MHz

Which resets the min frequency and the governor but as soon as I compile again with my IDE every time the governor and the min frequency changes again.

Any idea how I can disable that automatic change?

PS: If you need more details, just tell me where to find them and I will provide them

I admit it is a homework but I am lost in explaining the following command line:

WARNING: This is a so called FORK BOMB! This command line can and will crash your pc by consuming all RAM and CPU (trust me, I tried it...)

:(){ :|:& };:

As I know that I should do it alone here is what I have so far (searching for these chars is very discouraging).

1. The pipe enables to concatenate some commands together so that the first output is used by the second as input.
2. The & is to run a command in the background (basically used to start something from a shell which shouldn't be blocked by the command)

I guess that : is to fork? But here I am totally lost! I am willing to learn, so maybe someone have a good resource where I can read about that?