Typically the CPU runs for a while without stopping, then a system call is made to read from a file or write to a file. When the system call completes, the CPU computes again until it needs more data or has to write more data, and so on.
Some processes spend most of their time computing, while others spend most of their time waiting for I/O. The former are called compute-bound; the latter are called I/O-bound. Compute-bound processes typically have long CPU bursts and thus infrequent I/O waits, whereas I/O-bound processes have short CPU bursts and thus frequent I/O waits.
As CPU gets faster, processes tend to
get more I/O-bound.
Why and how?
Edited:
It’s not a homework question. I was studying the book (Modern Operating Systems by Tanenbaum) and found this matter there. I didn’t get the concept that’s why I am asking here. Don’t tag this question as a homework please.
With a faster CPU, the amount of time spent using the CPU will decrease (given the same code), but the amount of time spent doing I/O will stay the same (given the same I/O performance), so the percentage of time spent on I/O will increase, and I/O will become the bottleneck.
That does not mean that “I/O bound processes are faster”.