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CXL-DMSim: A Full-System CXL Disaggregated Memory Simulator With Comprehensive Silicon Validation
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DOI：10.1109/TCAD.2025.3607145.png)
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Abstract
En 中文
Compute Express Link (CXL) has emerged as a key enabler of memory disaggregation for future heterogeneous computing systems to expand memory on demand and improve resource utilization. However, CXL is still in its infancy stage and lacks commodity products on the market, thus necessitating a reliable system-level simulation tool for research and development. In this article, we propose CXL-DMSim (open-sourced at https://github.com/ferry-hhh/CXL-DMSim), an open-source full-system (FS) simulator to simulate CXL disaggregated memory systems with high fidelity at a gem5-comparable simulation speed. CXL-DMSim incorporates a flexible CXL memory expander model along with its associated device driver, and CXL protocol support with CXL.io and CXL.mem. It can operate in both the app-managed (AM) mode and the kernel-managed (KM) mode, with the latter using a dedicated NUMA-compatible mechanism. The simulator has been rigorously verified against a real hardware testbed with both FPGA- and ASIC-based CXL memory devices, which demonstrates the qualification of CXL-DMSim in simulating the characteristics of various CXL memory devices at an average simulation error of 3.4%. The experimental results using LMbench and STREAM benchmarks suggest that the CXL-FPGA memory exhibits a $\sim 2.88\times $ higher latency than local DDR, while the CXL-ASIC latency is $\sim 2.18\times $ ; CXL-FPGA achieves 45%-69% of local DDR memory bandwidth, whereas the number for CXL-ASIC is 82%-83%. The study also reveals that CXL memory can significantly enhance the performance of memory-intensive applications, improving by $23\times $ at most with limited local memory for Viper key-value database and approximately 60% in memory-bandwidth-sensitive scenarios such as MERCI. Moreover, the simulator's observability and expandability are showcased with detailed case studies, highlighting its great potential for research on future CXL-interconnected hybrid memory pools.
Keywords:
Protocols
Hardware
Emulation
Performance evaluation
Integrated circuit modeling
Design automation
Switches
Integrated circuit interconnections
Accuracy
Servers
Compute Express Link (CXL)
full-system (FS) simulator
hardware prototyping
memory disaggregation
performance benchmarking
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