The Split-Phase Synchronisation Technique: Reducing the Pessimism in the WCET Analysis of Parallelised Hard Real-Time Programs

In this paper we present the split-phase synchronisation technique to reduce the pessimism in the WCET analysis of parallelised hard real-time (HRT) programs on embedded multi-core processors. We implemented the split-phase synchronisation technique in the memory controller of the HRT capable MERASA multi-core processor. The split-phase synchronisation technique allows reordering memory requests and splitting of atomic RMW operations, while preserving atomicity, consistency and timing predictability. We determine the improvement of worst-case guarantees, that is the estimated upper bounds, for two parallelised HRT programs. We achieve a WCET improvement of up to 1.26 with the split-phase synchronisation technique, and an overall WCET improvement of up to 2.9 for parallel HRT programs with different software synchronisations.