Extended Global Dual Priority Algorithm for Multiprocessor Scheduling in Hard Real-Time Systems

In this paper we present a global scheduling method for shared memory multiprocessor systems that provides a fixed-priority preemptive scheduling of periodic tasks, hard aperiodic tasks and soft aperiodic tasks on a set of identical processors. The method is based on the functioning of the Dual Priority Scheduling Algorithm extended to work in a multiprocessor environment. This algorithm guarantees periodic tasks deadlines and achieves good mean soft aperiodic response times. We include hard aperiodic tasks, by using an acceptance control test for service. Extensive simulations show that the proposed algorithm gives both high guarantee ratios for hard aperiodic tasks still achieving low mean aperiodic response times.