Transient fault detection via simultaneous multithreading

Smaller feature sizes, reduced voltage levels, higher transistor counts, and reduced noise margins make future generations of microprocessors increasingly prone to transient hardware faults. Most commercial fault-tolerant computers use fully replicated hardware components to detect microprocessor faults. The components are lockstepped (cycle-by-cycle synchronized) to ensure that, in each cycle, they perform the same operation on the same inputs, producing the same outputs in the absence of faults. Unfortunately, for a given hardware budget, full replication reduces performance by statically partitioning resources among redundant operations. We demonstrate that a Simultaneous and Redundantly Threaded (SRT) processor---derived from a Simultaneous Multithreaded (SMT) processor---provides transient fault coverage with significantly higher performance. An SRT processor provides transient fault coverage by running identical copies of the same program simultaneously as independent threads. A...