Adaptive and application dependent runtime guided hardware prefetcher reconfiguration on the IBM POWER7

Abstract

Hardware data prefetcher engines have been extensively used to reduce the impact of memory latency. However, microprocessors' hardware prefetcher engines do not include any automatic hardware control able to dynamically tune their operation. This lacking architectural feature causes systems to operate with prefetchers in a fixed configuration, which in many cases harms performance and energy consumption. In this paper, a piece of software that solves the discussed problem in the context of the IBM POWER7 microprocessor is presented. The proposed solution involves using the runtime software as a bridge that is able to characterize user applications' workload and dynamically reconfigure the prefetcher engine. The proposed mechanisms has been deployed over OmpSs, a state-of-the-art task-based programming model. The paper shows significant performance improvements over a representative set of microbenchmarks and High Performance Computing (HPC) applications.