On-line scheduling for checkpointing imprecise computation

Abstract

When a failure occurs in a real-time system, the temporary loss of service and the recovery can cause a transient overload with an increase in the number of tasks that can not meet their timing constraints. The imprecise-computation technique allows one to trade off computation accuracy with computation time and offers therefore the necessary scheduling flexibility required during the recovery process after a failure. In this paper we investigate how the imprecise-computation approach can be combined with checkpointing; the result is a technique for fault-tolerance for real-time system. We define optimality criteria for the checkpointed imprecise-computation model In an earlier work we have described algorithms to statically schedule imprecise tasks to meet these criteria. These approaches are conservative for systems with very rare failures. We take advantage of new results in on-line scheduling of imprecise computation to design an algorithm that dynamically adapts to failure occurrences. Simulations are described to evaluate the performance of this algorithm. © 1993 IEEE.