Fault-Tolerant Scheduling of Mixed-Critical Applications on Multi-processor Platforms

There is a lack of mixed-criticality support in system-level design frameworks for dependable Network-on-Chip (NoC) -based multiprocessor systems. Such frameworks should address mixed-criticality in both computation and NoC communication. In Mixed-Critical (MC) systems, only the Safety-Critical (SC) parts have strict predictability and dependability requirements, but conventional methods design the whole system with pessimistic settings to ensure these requirements are satisfied. This however, results in under-utilization of computation and network resources, and a decrease in performance. In this work, we integrate support of MC applications into an existing system-level design framework of dependable NoC-based multiprocessors. This framework handles failures in both computation and inter-task communication. We address the under-utilization problem by proposing a mixed-critical scheduling method such that the overall system performance is increased but all deadlines of SC tasks are met even in the presence of transient faults. Our approach handles mixed-criticality not only in tasks but also in inter-task messages. Our experiments demonstrate performance improvement in different run-time execution environments and with different MC benchmark applications including a realistic robot control system. Performance improvement is achieved regardless of task graph size, NoC size or temporal redundancy level.