A Full-System Simulation Framework for CXL-Based SSD Memory System

Abstract

Compute eXpress Link (CXL) is a promising technology for memory disaggregation and expansion. Especially, CXL makes it more effectively for large-capacity storage devices such as Solid State Drive (SSD) to be deployed in the memory pool. However, CXL-based SSDs are still in early stages, necessitating the development of reliable simulation tools. In this paper, we propose CXL-SSD-Sim, the first open-source full-system simulator designed to simulate CXL-based SSD memory system. Constructed on the foundation of gem5 and SimpleSSD, CXL-SSD-Sim extends an high fidelity SSD memory expander model along with the corresponding device driver. In addition, CXL-SSD-Sim models a DRAM layer as a caching mechanism for the SSD, meticulously engineered to counteract latency issues inherent to CXL-based SSD memory access. Experiments are performed among five different memory devices with CXL-SSD-Sim in aspect of latency, bandwidth and real-world benchmark performance. These experiments serve to underscore the efficacy of our simulation tool in providing a comprehensive analysis of CXL-based SSD memory systems. The CXL-SSD-Sim simulator is available at https://github.com/WangYaohuii/CXL-SSD-Sim.