Enabling Design Space Exploration of DRAM Caches in Emerging Memory Systems

The increasing growth of applications' memory capacity and performance demands has led the CPU vendors to deploy heterogeneous memory systems either within a single system or via disaggregation. For instance, systems like Intel's Knights Landing and Sapphire Rapids can be configured to use high bandwidth memory as a cache to main memory. While there is significant research investigating the designs of DRAM caches, there has been little research investigating DRAM caches from a full system point of view, because there is not a suitable model available to the community to accurately study largescale systems with DRAM caches at a cycle-level. In this work we describe a new cycle-level DRAM cache model in the gem5 simulator which can be used for heterogeneous and disaggregated systems. We believe this model enables the community to perform a design space exploration for future generation of memory systems supporting DRAM caches.