In the era of large-scale AI model training and inference, the traditional PCIe bus is encountering unprecedented performance bottlenecks. Although PCIe 5.0 has pushed per-lane data rates to 32 GT/s, its fundamental architecture—point-to-point with no cache coherency—is increasingly inadequate for efficient collaboration among GPUs, FPGAs, and CPUs.
Enter CXL (Compute Express Link)—a protocol built on the PCIe physical layer but reimagined at the stack level, introducing cache coherency and memory semantics into a standard interconnect for the first time.
1. The Limits of PCIe: Bandwidth Isn’t Everything
While PCIe offers high bandwidth, every data transfer must traverse the OS kernel, driver layers, and memory copies, resulting in microsecond-level latency. In multi-GPU training setups, this “incoherency” leads to redundant data movement, severely degrading system efficiency.
2. Three Pillars of CXL Innovation
- CXL.io: Fully compatible with PCIe 5.0/6.0, preserving device enumeration and configuration;
- CXL.cache: Enables accelerators to directly access CPU caches with nanosecond response times;
- CXL.mem: Allows devices to share host memory with ultra-low latency—or even extend it as a pooled resource.
This transforms the GPU from a mere “compute unit” into an intelligent co-processor capable of dynamic memory sharing.
3. A Paradigm Shift in AI Infrastructure
Future AI servers will adopt a “CPU + Multi-GPU + CXL Memory Pool” topology. For example:
- Eight H100 GPUs sharing 1TB of unified system memory via CXL;
- An FPGA processing real-time sensor data and writing directly into a coherent address space;
- CXL Type 3 memory expansion cards scaling capacity on demand, avoiding prohibitive local DRAM costs.
According to Intel, by 2027, over 60% of data center accelerators will support CXL.
4. YZMU’s Forward-Looking Strategy
As a provider of high-speed interconnect solutions, YZMU (Shenzhen Yunzhou Interconnect Technology) has already initiated R&D on CXL 1.1/2.0–optimized cables:
- Low-loss differential pair design compliant with SFF-1017 / MCIO interfaces;
- Impedance control within ±5% tolerance to ensure signal integrity at 64 GT/s (PCIe 6.0);
- Modular form factors adaptable to backplanes, GPU risers, and edge AI chassis.
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