An adaptive filtering mechanism for energy efficient data prefetching

As data prefetching is used in embedded processors, it is crucial to reduce the wasted energy for improving the energy efficiency. In this paper, we propose an adaptive prefetch filtering (APF) mechanism to reduce the wasted bandwidth and energy as well as the cache pollution caused by useless prefetches. APF records the prefetch-victim address pairs of issued prefetches and collects information about which address in each pair is first accessed by the processor to guide the filtering of new generated useless prefetches. Meanwhile, filtered prefetches are recorded for building the feedback mechanism to avoid filtering useful prefetches. Experimental results demonstrate that APF reduces useless prefetches by an average of 53.81% with a mere 5.28% reduction of useful prefetches, thus reducing the memory access bandwidth consumption by 59.92% and the L2 cache energy by 6.19%. APF also improves the performance of several programs by reducing the cache pollution incurred by useless prefetches, thus gaining an average performance improvement of 2.12%.