Suppose you have a process which is I/O bound on multiple I/O resources. If instead of blocking on each one, you suspend that sequence of execution and move ont

Suppose you have a process which is I/O bound on multiple I/O resources. If instead of blocking on each one, you suspend that sequence of execution and move onto the next, resuming when you get the signal that the call is unblocked, you are handling the resources concurrently, but not in parallel. If you alter the program to spawn a separate thread for each, and let them all block, you will have a parallel solution.