Tech Explainer: What is CXL — and how can it help you lower data-center latency?


Latency is a crucial measure for every data center. Because latency measures the time it takes for data to travel from one point in a system or network to another, lower is generally better. Fortunately, the industry has come up with an open-source solution that provides a low-latency link between processors, accelerators and memory devices. It’s known as Compute Express Link, or CXL for short. Once a processor uses up the capacity of its direct-attached memory, it relies on an SSD. This introduces a three-order-of-magnitude latency gap that can hurt both performance and total cost of ownership (TCO). Another problem is that multicore processors are starving for memory bandwidth. The resulting deficit leads to suboptimal use of the additional processor cores, as the cores have to wait for data. CXL overcomes these issues by introducing a low-latency, memory cache coherent interconnect. Cache-coherence refers to IT architecture in which multiple processor cores share the same memory hierarchy, yet retain individual L1 caches. Today, there are three main types of CXL devices: Type 1: Any device without integrated local memory. Type 2: These devices include integrated memory, but also share CPU memory. Type 3: A class of devices designed to augment existing CPU memory.

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