SC Conference - Activity Details

Mitesh R. Meswani  (University of Texas at El Paso)

Thursday,  10:45AM - 11:00AM

Room 17A/17B

Simultaneous multithreading (SMT) allows multiple threads to execute concurrently on a core, potentially increasing utilization and throughput. However, contention for shared resources may not permit such performance gains. The IBM POWER5 provides software-controlled thread priorities, which allocate decode cycles to and control the degree of resource contention between the two hardware threads of a core. We have shown that at the default (equal) priorities 47% of co-schedules formed from 30 SPEC2000, SPEC2006, Stream, and LmBench benchmarks do not achieve best throughput. We have identified a critical subset of shared resources and performance counters to measure their utilization. We conjecture that, given a co-schedule of two threads and their SMT thread signatures, which describe each thread’s shared-resource usage, our methodology can be used to identify the “best” priority settings. We currently are extending single-resource signature benchmarks to multi-resource signature benchmarks, which will be used to predict optimal priority settings.