Two-phase colour-aware multicore real-time scheduler

A two-phase colour-aware real-time scheduler to reduce the contention caused by the cache coherence protocol due to accesses to shared cache partitions in a multicore processor is proposed. The first phase is a colour-aware task partitioning (CAP) algorithm that assigns tasks that share colours to a common processor whenever possible. The second phase is a dynamic colour-aware scheduler that detects cache coherence activities at run-time, preventing the execution of tasks that interfere with each other and thus reducing the contention caused by the cache coherence protocol. The authors compare the proposed scheduler with a CAP without run-time optimisation and with the best-fit decreasing heuristic in terms of deadline misses and tardiness of several task sets using a real-time operating system and a modern 8-core processor. The results indicate that the proposed scheduler improves deadline tardiness and provides hard real-time guarantees by combining cache and task partitioning with scheduling optimisations.