The size of input usually determines the performance of a sequential algorithm (or program) evaluated in terms of execution time. However, this is not the case for the parallel programs. When evaluating parallel programs, besides the input size, the computer architecture and also the number of the processors should be taken into consideration.
There are various of metrics to evaluate the performance of a parallel program. Execution time, Speedup and Efficiency are the most common metrics to measure the performance of a parallel program. We will discuss these metrics in the following subsections.