Is Semi-Partitioned Scheduling Practical?

Semi-partitioned schedulers are -- in theory -- a particularly promising category of multiprocessor real-time scheduling algorithms. Unfortunately, issues pertaining to their implementation have not been investigated in detail, so their practical viability remains unclear. In this paper, the practical merit of three EDF-based semi-partitioned algorithms is assessed via an experimental comparison based on real-time schedulability under consideration of real, measured overheads. The presented results indicate that semi-partitioning is indeed a sound and practical idea. However, several problematic design choices are identified as well. These shortcomings and other implementation concerns are discussed in detail.