For some reason one of my CPUs is always at 100% usage. Can anyone tell what the problem is from the pictures?

System Monitor resources view

Processes showing no serious CPU usage

System Monitor showing 100% CPU usage and switching to another CPU


  • I've seen this happen after a blanket font change in an old copy of Librewriter. What version system/Libre office are you running?
    – ubfan1
    Mar 20, 2018 at 3:10
  • 2
    Could you please edit your question to include the output of ps auxk -pcpu | head? Thanks. Mar 20, 2018 at 4:16

1 Answer 1


This happened to me today:

one cpu at 100 percent.png

From conky display the process ID is 14633, so in the terminal use:

rick@alien:~/Python$ ps -o ppid=14633
[1]+  Done                    gedit gmail-list-msg.py
rick@alien:~/Python$ ps -s -p 14633
  UID   PID          PENDING          BLOCKED          IGNORED           CAUGHT STAT TTY        TIME COMMAND
    0 14633 0000000000000000 0000000000000000 ffffffffffffffff 0000000000000000 R    ?          9:16 [kworker/4:0]
rick@alien:~/Python$ ps -s -p 3140
  UID   PID          PENDING          BLOCKED          IGNORED           CAUGHT STAT TTY        TIME COMMAND
 1000  3140 0000000000000000 0000000000000000 0000000000001000 0000000180010000 Sl   ?          0:07 /usr/lib/gnome
rick@alien:~/Python$ ps -s -p 17412
  UID   PID          PENDING          BLOCKED          IGNORED           CAUGHT STAT TTY        TIME COMMAND
 1000 17412 0000000000000000 0000000000010000 0000000000380004 000000004b817efb Ss   pts/19     0:00 bash

The 100% CPU usage was caused by using:

gedit gmail-list.msg.py &

gedit is used all the time as a background process and this is the first time I've seen 100% usage.

  • After closing gedit the offending process: kworker/4:0 is still using 100% of one CPU.
  • After closing gnome-terminal the offending process is still using 100% of one CPU.
  • After opening a new terminal using sudo kill 14633 doesn't help.
  • After using sudo kill 3140 there is no change.
  • Using sudo kill 17412 has no effect.

The only option left is to reboot and monitor if using gedit Xxxx & causes problem to reoccur.

First Reboot

After first reboot the problem shifted from CPU 4 to CPU 0 and offending kworker changed from 4 to 3.

Gnome terminal was automatically called by Startup Applications which seemed a regression of this bug: Debian Bug report logs - #594245 gnome-terminal using a lot of cpu

I deactivated gnome-terminal from Startup Applications and rebooted

Second Reboot

After second reboot no CPU is running at 100%.

I notice another problem where CPU frequency is running close to maximum of 3,000 MHz when it should be around 1,000 MHz with powersave governor active (which it is).

I also notice a crash report on pstree which is called by one of my bash script daemons that didn't wake up properly. I filed the automatic data collection bug report with Ubuntu and then rebooted.

Third Reboot

The BIOS start up screen seems frozen. Do a 1 second power button press and it acts like a 10 second power button press (hard power off).

Press power button again for cold boot (no longer a Restart / Warm Boot).

Power up after Shutdown

All is well again. Unknown what exactly went wrong but hopefully the documented steps helps others diagnose transient errors.

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