Dynamic prefetcher reconfiguration for diverse memory architectures

With the advent of stacked memory and new memory architectures, the heterogeneity of memory has been increasing. In the diverse memory technologies, each memory architecture has its own advantages and weaknesses. Considering the trade-offs, future systems are expected to support multiple memory architectures with a hybrid memory system. However, such diversity of memory architectures complicates the performance optimization of on-chip memory hierarchy. One of the key components affected by this trend is the hardware prefetcher. The available memory bandwidth highly affects the effectiveness of prefetchers, and the aggressiveness of prefetchers must be tuned for memory architectures as well as application behaviors. This paper investigates the effect of memory diversity on the prefetcher parameter selection, and proposes a dynamic parameter search mechanism to adjust the prefetch aggressiveness under various memory architectures. Using a general hill climbing scheme periodically, the mechanism adapts to the memory architectures and application behaviors effectively. In addition to such automatic tuning, the study improves the solution for cache pollution exacerbated by the increase of speculative data from more aggressive prefetchers in higher bandwidth memory. With the dynamic parameter search and pollution mitigation, the proposed framework improves the performance of applications by 12.4% on average compared to the prior scheme for tuning prefetch parameters.