An Analysis of Microarchitecture Vulnerability to Soft Errors on Simultaneous Multithreaded Architectures

Semiconductor transient faults (i.e. soft errors) have become an increasingly important threat to microprocessor reliability. Simultaneous multithreaded (SMT) architectures exploit thread-level parallelism to improve overall processor throughput. A great amount of research has been conducted in the past to investigate performance and power issues of SMT architectures. Nevertheless, the effect of multithreaded execution on a microarchitecture´s vulnerability to soft error remains largely unexplored. To address this issue, we have developed a microarchitecture level soft error vulnerability analysis framework for SMT architectures. Using a mixed set of SPEC CPU 2000 benchmarks, we quantify the impact of multithreading on a wide range of microarchitecture structures. We examine how the baseline SMT microarchitecture reliability profile varies with workload behavior, the number of threads and fetch policies. Our experimental results show that the overall vulnerability rises in multithreading architectures, while each individual thread shows less vulnerability. By considering both performance and reliability, SMT outperforms superscalar architectures. The SMT reliability and its tradeoff with performance vary across different fetch policies. With a detailed analysis of the experimental results, we point out a set of potential opportunities to reduce SMT microarchitecture vulnerability, which can serve as guidance to exploiting thread-aware reliability optimization techniques in the near future. To our knowledge, this paper presents the first effort to characterize microarchitecture vulnerability to soft error on SMT processors