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

Hardware data prefetcher engines have been extensively used to reduce the impact of memory latency. However, micro-processors ’ 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 microproces-sor 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 pre-fetcher 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 Perfor-mance Computing (HPC) applications. 1