Characterization of Error-Tolerant Applications when Protecting Control Data

Soft errors have become a significant concern and recent studies have measured the "architectural vulnerability factor" of systems to such errors, or conversely, the potential that a soft error is masked by latches or other system behavior. We take soft-error tolerance one step further and examine when an application can tolerate errors that are not masked. For example, a video decoder or approximation algorithm can tolerate errors if the user is willing to accept degraded output. The key observation is that while the decoder can tolerate error in its data, it can not tolerate error in its control. We first present static analysis that protects most control operations. We examine several SPEC CPU2000 and MiBench benchmarks for error tolerance, develop fidelity measures for each, and quantify the effect of errors on fidelity. We show that protecting control is crucial to producing error-tolerance, for without this protection, many applications experience catastrophic errors (infinite execution time or crashing). Overall, our results indicate that with simple control protection, the error tolerance of many applications can provide designers with considerable added flexibility when considering future challenges posed by soft errors