I run an old desktop mainboard as my homelab server. It runs Ubuntu smoothly at loads between 0.2 and 3 (whatever unit that is).

Problem:
Occasionally, the CPU load skyrockets above 400 (yes really), making the machine totally unresponsive. The only solution is the reset button.

Solution:

  • I haven’t found what the cause might be, but I think that a reboot every few days would prevent it from ever happening. That could be done easily with a crontab line.
  • alternatively, I would like to have some dead-simple script running in the background that simply looks at the CPU load and executes a reboot when the load climbs over a given threshold.

–> How could such a cpu-load-triggered reboot be implemented?

edit: I asked ChatGPT to help me create a script that is started by crontab every X minutes. The script has a kill-threshold that does a kill-9 on the top process, and a higher reboot-threshold that … reboots the machine. before doing either, or none of these, it will write a log line. I hope this will keep my system running, and I will review the log file to see how it fares. Or, it might inexplicable break my system. Fun!

  • @PlutoniumAcidOPEnglish
    2•3 months ago

    Thank you for these ideas, I will read up on systat+sar and give it a go.

    Also smart to have the script always running, sleeping, rather than launching it at intervals.

    I know all of this is a poor hack, and I must address the cause - but so far I have no clues what’s causing it. I’m running a bunch of Docker containers so it is very likely one of them painting itself into a corner, but after a reboot there’s nothing to see, so I am now starting with logging the top process. Your ideas might work better.