Enhancing Real-Time Schedules to Tolerate Transient Faults

We present a scheme to guarantee that the execution of real-time tasks can tolerate transient and intermittent faults assuming any queue-based scheduling technique. The scheme is based on reserving su cient slack in a schedule such that a task can be re-executed before its deadline without compromising guarantees given to other tasks. Only enough slack is reserved in the schedule to guarantee fault tolerance if at most one fault occurs within a time interval. This results in increased schedulability and a very low percentage of deadline misses even if no restriction is placed on the fault separation. We provide two algorithms to solve the problem of adding fault tolerance to a queue of real-time tasks. The rst is a dynamic programming optimal solution and the second is a greedy heuristic which closely approximates the optimal.