We have an Ubuntu based mini computer at which serves as little more than a network switch. CPU and other resource utilization should be next to nothing, but frequently this computer would have CPU temperatures around 80 degrees Celsius, and when you would watch the resource monitor the CPU activity was all over the place. Despite the computer only really showing a few percent of CPU usage, if you went toe the Resources Tab of System Monitor, the per-core CPU activity was all over the place.
As I mentioned, the computer in question is a simple network appliance that would never need to print, and upon closer inspection, it was the Linux “CUPS” Service. Once we disabled that, the CPU settled right down.
CUPS, once known as the “Common UNIX Printing System” is a service that uses other protocols, such as Bonjour, to scan that network and find printers to more easily add them and be ready to print to those devices. If you’re on a computer that is never going to print, you don’t need CUPS running!
To quickly avail yourself of CUPS, simply stop and disable the service:
sudo systemctl stop CUPS
sudo systemctl disable CUPS
sudo systemctl mask CUPSStopping it will halt it the service so you can see if it’s causing the issue you’re seeing. Disabling prevents it from starting automatically after a reboot. Masking CUPS may also be a way to prevent it from being triggered by other services, beyond just simple “automatic start up.”
As I mentioned, once that was done our CPU temp dropped by half and the CPU utilization became almost nothing. This will obviously also have the added benefit of power savings and longer life if the system ends up on battery backup for any length of time, which will increase our reliability and up-time.