CPU usage is currently expressed as the percentage of time spent running
during the entire lifetime of a process. This is not ideal, and it does not
conform to the standards that ps otherwise conforms to. CPU usage is unlikely
to add up to exactly 100%.
This explains why my nagios checks for processes with >90% CPU use doesn’t work.
It’s logical when you think it through, but the nagios check is very misleading because it doesn’t mention this at all, just talks about CPU.
Sigh, let’s try with sar instead.