Inherent Time Redundancy (ITR): Using Program Repetition for Low-Overhead Fault Tolerance

Abstract

A new approach is proposed that exploits repetition inherent in programs to provide low-overhead transient fault protection in a processor. Programs repeatedly execute the same instructions within close time periods. This can be viewed as a time redundant re-execution of a program, except that inputs to these inherent time redundant (ITR) instructions vary. Nevertheless, certain microarchitectural events in the processor are independent of the input and only depend on the program instructions. Such events can be recorded and confirmed when ITR instructions repeat. In this paper, we use ITR to detect transient faults in the fetch and decode units of a processor pipeline, avoiding costly approaches like structural duplication or explicit time redundant execution.