Atop is an ASCII full-screen performance monitor, similar to the top
command. At regular intervals, it shows system-level activity related to
the CPU, memory, swap, disks and network layers, and it shows for every
active process the CPU utilization in system and user mode, the virtual
and resident memory growth, priority, username, state, and exit code. The
process level activity is also shown for processes which finished during
the last interval, to get a complete overview about the consumers of things
such as CPU time. Atop only shows the active system-resources and processes,
and only shows the deviations since the previous interval.