Non-Referenced Prefetch (NRP) Cache for Instruction Prefetching

A new conceptual cache, NRP (Non-Referenced Prefetch) cache, is proposed to improve the performance of instruction prefetch mechanisms which try to prefetch both the sequential and non-sequential blocks under the limited memory bandwidth. The NRP cache is used in storing prefetched blocks which were not referenced by the CPU, while these blocks were discarded in other previous prefetch mechanisms. By storing the nonreferenced prefetch blocks in the NRP cache, both cache misses and memory traffics are reduced. A prefetch method to prefetch both the sequential and the non-sequential instruction paths is designed to utilize the effectiveness of the NRP cache. The results from trace-driven simulation show that this approach provides an improvement in memory access time than other prefetch methods. Particularly, the NRP cache is more effective in a lookahead prefetch mechanism that can hide longer memory latency. Also, the NRP cache reduces 50% ¸ 112% of the additional memory traffics requi..