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Compute Express Link, or CXL is dramatically changing the way memory is used in computer systems. Tutorials at the IEEE Hot Chips Conference and at the recent SNIA Storage Developers Conference explored how CXL works and how it will change the ways we do computing. In addition, recent announcements by Colorado startup, IntelliProp, on their Omega Memory Fabric chips pave the way for implementation of CXL to enable memory pooling and composable infrastructure.
The initial applications for CXL have been for memory expansion for individual CPUs, but CXL will have the biggest impact in sharing many different types of memory technology (DRAM and persistent memory) between CPUs. The image below (from the CXL Hot Chips tutorial) shows the different way that memory can be shared with CXL.
Uses for CXL connected memory
As Yang Seok Ki, VP from Samsung Electronics said at the SNIA SDC, CXL is an industry-supported cache-coherent interconnect for processors, memory expansion and accelerators. CXL version 1.0 and 2.0 have been released (working with PCIe 5.0) and in early August, at the Flash Memory Summit, the CXL version 3.0 was released that works with the faster PCIe 6.0 interconnect. CXL 3.0 also enables multi-level switching and memory fabrics and peer-to-peer direct memory access.
The presentation also outlined how CXL enables version 2.0 enabled medium memory available to a CPU through a local CXL connection and far memory through a CXL version 3.0 switched network, as shown below.
CXL enables near, medium and far memory
Near memory is directly connected to the CPU. Some of the first CXL products available are medium memory expander products that provide additional memory to a CPU. CXL opens the door to memory tiering providing similar trade-offs in performance and cost as are possible with storage tiering.
IntelliProp just announced its Omega Memory Fabric chips. The chips incorporate the CXL standard along with the company’s Fabric Management Software and Network Attached Memory (NAM) system. IntelliProp also announced three field-programmable gate arrays (FPGA) products that incorporate its Omega Memory Fabric. The company says that its memory-agnostic innovation will help lead to the adoption of composable memory leading to significant improvements in data center energy consumption and efficiency. The company says that its Omega Memory Fabric has the following features:
Omega Memory Fabric Features, incorporating the CXL Standard
The three FPGA solutions connect CXL devices to CXL hosts and they are a adapter, a switch and a fabric manager. IntelliProp says that ASIC solutions will be available in 2023. The company says the solutions connect CXL devices to CXL hosts, allowing data centers to increase performance, scale across dozens to thousands of host nodes, consume less energy since data travels with fewer hops and enable mixed use of shared DRAM (fast memory) and shared SCM (slow memory).
CXL is poised to change the way memory is used in computer architectures according to a 2022 Hot Chips tutorial and talks at the SNIA SDC. IntelliProp introduced the company’s Open Memory Fabric technology and three FPGA solutions for enabling CXL enabled memory fabrics.