Early comparison and decision strategies for datapaths that recover from transient faults

Rollback and retry is a common approach used to achieve error recovery in datapaths that tolerate transient faults. In this approach, each segment of a computation is duplicated and the results are compared using fault-tolerant comparators. If the compared values are unequal, the segment is rolled back to the preceding correct state (rollback point) and retried from that state. We introduce early comparison and rollback strategies for use in such datapaths. These strategies utilize comparators during the computational portion of the segment and can initiate a rollback before the segment is completed. We illustrate through examples how these strategies can reduce hardware costs (number of comparators needed) and the delay in recovering from a transient fault compared to conventional strategies