Measuring Time

A simple way to measure execution time of a program is to use the unix time program:

time sort input.txt

The output will give three times labeled, real, system and user. We are interested in the real time, since this represents execution time from start to finish.

Since the goal here is to produce a standard graph, you are going to want to ‘time’ your program/code with different input sizes. Breaking up the input to appropriate sizes is completely application dependent, and largely depends on the type of input. Your input might be a million samples, and therefore you could ‘time’ program exeuction on 1000, 10000, 25000, 50000, and 100000 samples. The goal here is to simply see how execution time responds to different input sizes, so you don’t need to scale your samples very high. But you do want to get at least 4 points, and have them spaced to create a clear graph.