On the scheduling of fault-tolerant mixed-criticality systems

We consider in this paper fault-tolerant mixed-criticality scheduling, where heterogeneous safety guarantees must be provided to functionalities (tasks) of varying criticalities (importances). We model explicitly the safety requirements for tasks of different criticalities according to safety standards, assuming hardware transient faults. We further provide analysis techniques to bound the effects of task killing and service degradation on the system safety and schedulability. Based on our model and analysis, we show that our problem can be converted to a conventional mixed-criticality scheduling problem. Thus, we broaden the scope of applicability of the conventional mixed-criticality scheduling techniques. Our proposed techniques are validated with a realistic flight management system application and extensive simulations.