A Parametrized Branch-and-Bound Strategy for Scheduling Precedence-Constrained Tasks on a Multiprocessor System

In this paper we experimentally evaluate the performance of a parametrized branch-and-bound (B&B) algorithm for scheduling real-time tasks on a multiprocessor system. The objective of the B&B algorithm is to minimize the maximum task lateness in the system. We show that a last-in-first-out (LIFO) vertex selection rule clearly outperforms the commonly used least-lower-bound (LLB) rule for the scheduling problem. We also present a new adaptive lower-bound cost function that greatly improves the performance of the B&B algorithm when parallelism in the application cannot be fully exploited on the multiprocessor architecture. Finally, we evaluate a set of heuristic strategies, one of which generates near-optimal results with performance guarantees and another of which generates approximate results without performance guarantees.