EDF-Adaptive: A New Semipartitioned Scheduling Algorithm for Multiprocessor Real-Time

Most of the multiprocessor real-time scheduling algorithms follow the partitioned approach, the global approach, or the semipartitioned approach which is a hybrid of the first two by allowing a small subset of tasks to migrate. EDF-fm (Earliest Deadline First-based Fixed and Migrating) and EDF-os (Earliest Deadline First-based Optimal Semipartitioned) are semipartitioned approaches and were proposed for soft real-time sporadic task systems. Despite their desirable property that migrations are boundary-limited such as they can only occur at job boundaries, EDF-fm and EDF-os are not always optimal and have higher tardiness and cost of overheads due to task migration. To address these issues, in this paper, we classify the systems into different types according to the utilization of their tasks and propose a new semipartitioned scheduling algorithm, earliest deadline first-adaptive, dubbed as EDF-adaptive. Our experiments show that EDF-adaptive can achieve better performance than EDF-fm and EDF-os, in terms of system utilization and tardiness overhead. It is also proved that EDF-adaptive is able to lessen the task migration overhead, by reducing the number of migrating jobs and the number of processors to which a task is migrated.

Global Multiprocessor Scheduling with Job Level Priority Assignment

In the field of real-time multiprocessor scheduling, researchers have found that global scheduling on average results in better resource utilization than partitioned scheduling, and is more robust in the presence of timing errors. In this paper, we present a global scheduling algorithm JPA with Job-level Priority Assignment for sporadic task systems that can be viewed as a generalization of both FPS and EDF. We also introduce JPA's efficient variant, which greatly reduces the runtime overhead comparing with JPA. As will be shown by the experiments, JPA indeed exhibits much better performance than the state-of-the-art multiprocessor scheduling/analysis techniques based on FPS and EDF.