A Programmable Memory Hierarchy for Prefetching Linked Data Structures

Prefetching is often used to overlap memory latency with computation for array-based applications. However, prefetching for pointer-intensive applications remains a challenge because of the irregular memory access pattern and pointer-chasing problem. In this paper, we use a programmable processor, a prefetch engine (PFE), at each level of the memory hierarchy to cooperatively execute instructions that traverse a linked data structure. Cache blocks accessed by the processors at the L2 and memory levels are proactively pushed up to the CPU.We look at several design issues to support this programmable memory hierarchy. We establish a general interaction scheme among three PFEs and design a mechanism to synchronize the PFE execution with the CPU. Our simulation results show that the proposed prefetching scheme can reduce up to 100% of memory stall time on a suite of pointer-intensive applications, reducing overall execution time by an average 19%.