From RUN to QPS: new trends for optimal real-time multiprocessor scheduling

Abstract

Until recently, there has been a common belief that optimal multiprocessor real-time scheduling algorithms necessarily incur a high number of task preemptions and migrations. New scheduling algorithms have shown that this is not the case. In this paper, we explain why two of these algorithms, reduction to uniprocessor (RUN) and quasi-partition scheduling (QPS), achieve optimality with only a few preemptions and migrations, exhibiting their similarities and differences. We also compare these two algorithms via simulations, highlighting the consequences of their differences in their performance. By putting RUN and QPS side-by-side, we bring about their fundamental properties and help in the understanding of the multiprocessor real-time scheduling problem.