In parallel computing, Amdahl's law is mainly used to predict the theoretical maximum speedup for program processing using multiple processors. If we denote the speed up by S then Amdahl’s law is given by the formula:
where P is the proportion of a system or program that can be made parallel, and 1-P is the proportion that remains serial. My question is: how can we compute or estimate P for a given program?
More specifically, my question has two parts:
How can we compute P theoretically? How can we compute P in practice?