I can't see a mention of it here, or on the original page, so IMO it's worth pointing out a utility that you will most likely already have installed on your Lin

I can't see a mention of it here, or on the original page, so IMO it's worth pointing out a utility that you will most likely already have installed on your Linux machine: vmstat. Just run: vmstat 3 And you'll get a running breakdown of CPU usage (split into user/system), and a breakdown of 'idle' time (split into actual idle time and time waiting for I/O (or some kinds of locks). The '3' in the command line is just how long the stats are averaged over, I'd recommend using 3+ to average out bursts of activity on a fairly steady-state system.