On the performance difference between theory and practice for parallel algorithms

The performance of parallel algorithms is often inconsistent with their preliminary theoretical analyses. Indeed, the difference is increasing between the ability to theoretically predict the performance of a parallel algorithm and the results measured in practice. This is mainly due to the accelerated development of advanced parallel architectures, whereas there is still no agreed model for parallel computation, which has implications for the design of parallel algorithms and for the manner in which parallel programming should be taught.

In this study, we examined the practical performance of Cormen’s Quicksort parallel algorithm. We determined the performance of the algorithm with different parallel programming approaches and examine the capacity of theoretical performance analyses of the algorithm for predicting the actual performance. This algorithm is used for teaching theoretical and practical aspects of parallel programming to undergraduate students. We considered the pedagogic implications that may arise when the algorithm is used as a learning resource for teaching parallel programming.