Core Concepts
CXL is an open industry-standard interconnect that addresses key computing challenges by enabling resource pooling, memory scalability, and fine-grained data sharing.
Abstract
The content introduces the Compute Express Link (CXL) protocol, covering CXL 1.0, CXL 2.0, and CXL 3.0 standards. It discusses the challenges addressed by CXL, such as coherency access to system memory, memory scalability issues, memory and compute inefficiency due to stranding, and fine-grained data sharing in distributed systems. The article also explains the enhancements introduced in CXL 2.0 for resource pooling, quality-of-service for memory, device pooling, and global persistent flush.
Introduction to CXL and its importance in the industry.
Challenges faced by traditional interfaces like PCIe and DDR.
Detailed explanation of how CXL addresses these challenges through its protocols.
Overview of the enhancements in CXL 2.0 for resource management.
Explanation of pool management using the Fabric Manager (FM).
Stats
"A PCIe device cannot cache system memory to exploit temporal or spatial locality or to perform atomic sequences of operations."
"For example, a x16 Gen5 PCIe port at 32 GT/s offers 256 GB/s with 64 signal pins."
"Another scaling challenge is that DRAM memory cost per bit has recently stayed flat."
Quotes
"CXL coherence is decoupled from host-specific coherence protocol details."
"CXL.cache enables a device to cache host memory using the MESI coherence protocol."