Compute Express Link(CXL), the Next Generation Interconnect - Overview and the Status of Linux
Talkat LinuxCon @ Open Source Summit Japan 2023 · on Tuesday, 2023-12-05· at 14:00· Conference Room 1 (3F Level), Ariake Central Tower Hall + Conference, 3-7-18, Ariake, Koto-ku·
summary
CXL is now at CXL 3.1 with fabric support (port‑based routing, 12‑bit port IDs for ~4,096 nodes) and global integrated memory; Linux has a basic CXL memory driver and ndctl-style tools to detect devices and configure regions. Kernel 6.1 adds demotion/promotion NUMA handling to mitigate CXL latency tearing, but memory hot‑remove still fails when pages are pinned. CXL 3.0 introduces dynamic capacity devices and sharing; on‑device ODP (on‑demand paging) is the practical path to scalable hot‑plug removal.
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chapters (18)
- 0:00Introduction
- 2:20What is CXL
- 4:07Why CXL needed
- 7:15CXL cache-coherent
- 9:08CXL device types
- 11:59Type 3 memory features
- 16:20CXL 3.0/3.1 updates
- 17:25CXL 3.0 fabric
- 19:19CXL 3.0 coherency
- 21:29Memory sharing hosts
- 22:36CXL 3.1 security
- 24:04Linux CXL support
- 25:10Memory tiering challenges
- 28:52Demotion/promotion
- 30:15Memory hot-plug issues
- 33:10Dynamic capacity device
- 35:00On-demand paging
- 36:07Conclusion
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