Exploring the performance limits of simultaneous multithreading for memory intensive applications

Simultaneous multithreading (SMT) has been proposed to improve system throughput by overlapping instructions from multiple threads on a single wide-issue processor. Recent studies have demonstrated that diversity of simultaneously executed applications can bring up significant performance gains due to SMT. However, the speedup of a single application that is parallelized into multiple threads, is often sensitive to its inherent instruction level parallelism (ILP), as well as the efficiency of synchronization and communication mechanisms between its separate, but possibly dependent threads. Moreover, as these separate threads tend to put pressure on the same architectural resources, no significant speedup can be observed.