pidstat
Reading the systemPackage: sysstat
The same readings as sar, per process: which PID burns the CPU, writes to disk, or switches context too often. The link between "the machine is slow" and "it is this program".
What its options do in the lessons
From the same glossary the lessons render under their commands, so the two cannot disagree.
pidstat -d- The per-process I/O report:
kB_rd/s,kB_wr/s, cancelled writes andiodelay. Needs root for processes you do not own.