A Fault-Tolerant Voting Scheme for Multithreaded Environments

Voting schemes are widely used in fault-tolerant systems, mainly systems which imply temporal or component redundancy. We present a voting scheme for multithreaded environments which is based on the observation that a fault-tolerant system which does not know its history can not distinguish between transient (SEUs) and permanent errors, caused by use of a faulty component. The history of errors is used to predict future errors and to determine if a permanent or transient error occurred. Only in the former case a repair is necessary; in the latter case recovery is sufficient. Using prediction and credibility points we are able to tell if a system failure is likely to occur soon. The more credibility a version has, the more likely it will compute a correct result. Therefore we can use credibility points in connection with thread priorisation to increase performance.