Reader-Writer Synchronization for Shared-Memory Multiprocessor Real-Time Systems

Reader preference, writer preference, and task-fair reader-writer locks are shown to cause undue blocking in multiprocessor real-time systems. A new phase-fair reader-writer lock is proposed as an alternative that significantly reduces worst-case blocking for readers and an efficient local-spin implementation is provided. Both task- and phase-fair locks are evaluated and contrasted to mutex locks in terms of hard and soft real-time schedulability under consideration of runtime overheads on a multicore computer. With the transition to multicore architectures by most (if not all) major chip manufacturers, multiprocessors are now a standard deployment platform for (soft) real-time applications.