Semi-Partitioned Hard-Real-Time Scheduling under Locked Cache Migration in Multicore Systems

As real-time embedded systems integrate more and more functionality, they are demanding increasing amounts of computational power that can only be met by deploying multicore architectures. The use of multicore architectures with on-chip memory hierarchies and shared communication infrastructure in the context of real-time systems poses several challenges for task scheduling. In this paper, we present a predictable semi-partitioned strategy for scheduling a set of independent hard-real-time tasks on homogeneous multicore platforms using cache locking and locked cache migration. Semipartitioned scheduling strategies form a middle ground between the two extreme approaches, namely global and partitioned scheduling. By making most tasks non-migrating (partitioned), runtime migration overhead is minimized. On the other hand, by allowing some tasks to migrate among cores, schedulability of task sets may be improved. Simulation results demonstrate the effectiveness of our approach in improving task set schedulability over purely partitioned approaches while maintaining real-time predictability of migrating tasks. In our simulations, we achieve an average increase in utilization of 37.31% and an average increase in density of 81.36% compared to purely partitioned task allocation.