Performance Analysis of Simultaneous Multithreading in a PowerPC-based Processor

Simultaneous multithreading (SMT) is an approach to address the well-known problems of memory accesses increasingly dominating processor execution time and of limited instruction level parallelism. Previous research has explored the benefits and limitations of SMT based on specific processor architectures under a variety of workloads. In this paper, we present a performance analysis of SMT in a PowerPC-based wide superscalar processor architecture under a broad range of workloads, which includes combinations of TPC-C, SPECint and SPECfp. Although some of our results are consistent with previous work, our results also demonstrate some differences and we use these results to explore and identify the primary causes of such differences. This includes an investigation of thread characteristics that work well together in SMT environments, and thread characteristics that do not work well together.