Lazy Prefetching

High latency of memory accesses is critical to the performance of shared memory multiprocessors. The technology trends indicate that this gap between processor and memory speeds is likely to increase in the future. To cope with memory latency problem two softwarecontrolled techniques have been investigated: prefetching and remote write. Prefetching is a consumer-initiated technique which moves data close to the processor before they are actually needed by explicit execution prefetch instruction. Remote write, a producer-initiated technique moves data close to the processor estimated to be the next consumer. However these techniques can degrade the performance in the case of misprediction of future needs and/or consumers. The new method called lazy prefetching which combines good properties of prefetching and remote write techniques is presented in this paper. The experimental methodology used for performance analysis is also described.