Extending the effectiveness of 3D-stacked DRAM caches with an adaptive multi-queue policy

Abstract

3D-integration is a promising technology to help combat the "Memory Wall" in future multi-core processors. Past work has considered using 3D-stacked DRAM as a large last-level cache (LLC). While significant performance benefits can be gained with such an approach, there remain additional opportunities beyond the simple integration of commodity DRAM chips. In this work, we leverage the hardware organization typical of DRAM architectures to propose new cache management policies that would otherwise not be practical for standard SRAM-based caches. We propose a cache where each set is organized as multiple logical FIFO or queue structures that simultaneously provide performance isolation between threads as well as reduce the number of entries occupied by dead lines. Our results show that beyond the simplistic approach of stacking DRAM as cache, such tightly-integrated 3D architectures enable new opportunities for optimizing and improving system performance.