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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!

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[–] possiblylinux127@lemmy.zip 2 points 6 months ago (1 children)

Here's a better suggestion. Why don't you see if you can find out what's causing the issue? It sounds a like a problem occurring in userspace. Try running htop

[–] PlutoniumAcid@lemmy.world 0 points 6 months ago (1 children)

You know you are right, and I've tried. I can manually monitor but it doesn't happen just then. I don't know yet what causes it, I can only assume it's one of the Docker containers because the machine is doing nothing else.

I am doing this to find out how often it happens, how quickly it happens, and what's at the top when it happens.

[–] vegetaaaaaaa@lemmy.world 1 points 6 months ago

I can manually monitor but it doesn’t happen just then

Setup proper monitoring with history. That way yo don't have to babysit the server, you can just look at the charts after a crash. I usually go with netdata

[–] cron@feddit.de 1 points 6 months ago

Just as a side note, the load factor can also mean that processes are limited by IO:

Unix systems traditionally just counted processes waiting for the CPU, but Linux also counts processes waiting for other resources -- for example, processes waiting to read from or write to the disk.

Source

[–] marcos@lemmy.world 0 points 6 months ago (1 children)

Have you tried turning your swap off?

[–] PlutoniumAcid@lemmy.world 0 points 6 months ago (1 children)

Nope, haven't. It says I have 2 GB of swap on a 16 GB RAM system, and that seems reasonable.

Why would you recommend turning swap off?

[–] marcos@lemmy.world 1 points 6 months ago

To check if your problem is caused by excessive memory usage requiring constant swapping. If it is, turning swap off will make some process be killed instead of slowing the computer down.