Using value similarity of registers for soft error mitigation

Soft errors caused by the cosmic particles or the radiation from the packaging material of the integrated circuits are an increasingly important design problem. With the shrinking feature sizes, the datapath components of the out-of-order superscalar pipeline are becoming more prone to soft errors. Being the major data holding component in contemporary microprocessors, the register file has been an important part of the processor on which researchers offered many different schemes to protect against soft errors. We start with the observation that many of the stored values inside the register file have very small Hamming distances when compared to each other. After showing this analysis results we propose a soft error correction scheme that makes use of the presence of multiple register values that have zero Hamming distance from each other. We use this already available redundancy along with parity protection to achieve error correction for many of the stored values. Our results show that, by employing schemes that make use of the already available copies of the values inside the register file, it is possible to detect and correct 39.0% of the errors with an additional power consumption of 18.9%.