The Compute Express Link (CXL) is an open industry-standard interconnect between processors and devices such as accelerators, memory buffers, smart network interfaces, persistent memory, and solid-state drives. CXL offers coherency and memory semantics with bandwidth that scales with PCIe bandwidth while achieving significantly lower latency than PCIe. All major CPU vendors, device vendors, and datacenter operators have adopted CXL as a common standard. This enables an inter-operable ecosystem that supports key computing use cases including highly efficient accelerators, server memory bandwidth and capacity expansion, multi-server resource pooling and sharing, and efficient peer-to-peer communication. This survey provides an introduction to CXL covering the standards CXL 1.0, CXL 2.0, and CXL 3.0. We further survey CXL implementations, discuss CXL's impact on the datacenter landscape, and future directions.

翻译：计算快速链接（CXL）是一种开放的工业标准互连技术，用于连接处理器与加速器、内存缓冲器、智能网络接口、持久内存及固态硬盘等设备。该技术提供缓存一致性及内存语义支持，其带宽随PCIe带宽同步扩展，同时实现显著低于PCIe的延迟。当前所有主要CPU厂商、设备制造商及数据中心运营商均已将CXL采纳为通用标准，由此构建支持关键计算场景的互操作生态系统，具体涵盖高效能加速器、服务器内存带宽与容量扩展、多服务器资源池化共享、以及高效的端到端通信。本综述系统介绍CXL技术，覆盖CXL 1.0、CXL 2.0及CXL 3.0标准体系，进一步探讨CXL实现方案及其对数据中心架构的影响，并展望未来发展方向。