发表机构
Sogang University; ETRI（西江大学; 韩国电子通信研究院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
提出CXDVirt内核模块仿真器，移除虚拟机开销，通过devdax和自定义缺页路径模拟CXL-SSD双峰延迟，降低未命中延迟1.4-1.6倍，支持策略研究。
AI 中文摘要
CXL-SSD通过设备内的小型DRAM缓存，承诺对NAND容量实现内存语义访问，但稀缺的硬件使得仿真成为CXL-SSD研究的核心。Cylon是一款最先进的仿真器，它在虚拟机中运行工作负载，拦截DRAM未命中以注入NAND延迟。我们证明，这种虚拟机机制每次未命中增加超过3微秒的延迟，超过了高性能NAND读取延迟，而重复的虚拟机退出使尾部未命中延迟膨胀数倍。我们提出CXDVirt，一种基于内核模块的CXL-SSD仿真器，完全移除虚拟机：设备通过主机devdax暴露，命中通过MMU原生运行，自定义缺页路径在未命中时模拟NAND延迟。CXDVirt保留了CXL-SSD的双峰延迟特征，同时将每次未命中延迟降低1.4-1.6倍（P99.9时降低4.1倍）；在八个线程下，其未命中延迟仅翻倍，而Cylon在QEMU全局锁后为8-9倍。在没有NAND流量时，CXDVirt与远程DRAM的差距在5%以内，而Cylon慢3.1-3.6倍，并支持可配置的驱逐和预取策略研究。
英文摘要
CXL-SSDs promise memory-semantic access to NAND-scale capacity through a small in-device DRAM cache, but scarce hardware makes emulation central to CXL-SSD research. Cylon, a state-of-the-art emulator, runs workloads in a VM, intercepting DRAM misses to inject NAND latency. We show this VM machinery adds over 3$μs$ per miss, exceeding high-performance NAND read latency, while repeated VM exits inflate tail miss latencies several-fold. We present CXDVirt, a kernel-module-based CXL-SSD emulator that removes the VM entirely: the device is exposed through host devdax, hits run natively via the MMU, and a custom page-fault path models NAND latency on misses. CXDVirt preserves CXL-SSDs' bimodal latency profile while reducing per-miss latency 1.4-1.6$\times$ (4.1$\times$ at P99.9); with eight threads its miss latency only doubles, against 8-9$\times$ for Cylon behind QEMU's global lock. CXDVirt stays within 5% of remote DRAM without NAND traffic, where Cylon is 3.1-3.6$\times$ slower, and enables configurable eviction and prefetch policy studies.
Comments6 pages, 8 figures. To be presented at the 17th International Workshop on Performance Modeling, Benchmarking and Simulation of High Performance Computer Systems (PMBS), held in conjunction with SC26
