note~

Ruby 2.5 (YARV interpreter, red thread)

Resident set size (rss)to record memory
https://github.com/schneems/get_process_mem


Running this code would give an output similar to this:

****CPU Bound****
CPU time	=	5038
Wall time	=	5142

****IO Bound****
CPU time	=	337898
Wall time	=	475864
This clearly shows that on a single CPU core, CPU time and Wall time are nearly equal when running purely CPU bound instructions whereas CPU time is always less that Wall time when running I/O bound instructions.