Exploiting Idle cycles for Algorithm Level Re-Computing

Duplication and comparison of results at checkpoints was Although algorithm level re-computing techniques can used in [10], while duplication and comparison of results as soon as they become available was used in [11]. trade-off the detection capability of Concurrent Error Hamilton and Orailolu presented a roll forward based Detection (CED) vs. time overhead, it results in 100% transient fault recovery technique by grouping operations time overhead when the strongest CED capability is in a scheduled and check-pointed Control Data Flow achieved. Using the idle cycles in the data path to do the re-computation can reduce this time overhead. However Graph (CDFG) of an algorithm into non-overlapping sub dependencies between operations prevent the re- CDFGs called strings [1]. Upon detecting a fault the faulty string is recomputed in parallel with the computation from fully utilizing the idle cycles. computation of the subsequent strings. This roll forward Deliberately breaking some of these data dependencies can further reduce the time overhead associated with technique reduces the performance overhead associated algorithm level re-computing. with recovery