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 s egment of a computation is duplicated and the results are compared usi ng 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 rollb ack strategies for use in such datapaths, These strategies utilize com parators during the computational portion of the segment and can initi ate a rollback before the segment is completed. We illustrate through examples how these strategies can reduce hardware costs (number of com parators needed) and the delay in recovering from a transient fault co mpared to conventional strategies.