CXLSim: A Simulator for CXL Memory Expander

Compute Express Link (CXL), a cache-coherent interconnect protocol for CPUs and PCIe devices, has emerged as a promising solution for memory expansion. In this work, we develop a CXL simulator built upon GEM5 and QEMU to assess the system-wide performance impacts based on varying attributes of CXL devices, such as memory capacity and latency. The simulator directs memory traffic to either system memory or the CXL memory expander, tracks cache hit/miss ratios, and projects application performance. Our simulation study demonstrates that the simulator accurately predicts application performance.