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The Liberty Research Group

Fault Tolerance Project

DAFT: Decoupled Acyclic Fault Tolerance [abstract] (ACM DL, PDF)
Yun Zhang, Jae W. Lee, Nick P. Johnson, and David I. August
Proceedings of the 19th International Conference on Parallel Architectures and Compilation Techniques (PACT), September 2010.
Accept Rate: 17% (46/266).
Selected by the Program Committee as a "top paper" for inclusion in a special issue of the International Journal of Parallel Programming (IJPP).

Higher transistor counts, lower voltage levels, and reduced noise margin increase the susceptibility of multicore processors to transient faults. Redundant hardware modules can detect such errors, but software transient fault detection techniques are more appealing for their low cost and flexibility. Recent software proposals double register pressure or memory usage, or are too slow in the absence of hardware extensions, preventing widespread acceptance. This paper presents DAFT, a fast, safe, and memory efficient transient fault detection framework for commodity multicore systems. DAFT replicates computation across multiple cores and schedules fault detection off the critical path. Where possible, values are speculated to be correct and only communicated to the redundant thread at essential program points. DAFT is implemented in the LLVM compiler framework and evaluated using SPEC CPU2000 and SPEC CPU2006 benchmarks on a commodity multicore system. Results demonstrate DAFT's high performance and broad fault coverage. Speculation allows DAFT to reduce the performance overhead of software redundant multithreading from an average of 200% to 38% with no degradation of fault coverage.