ARM CoreLink Fabric Links 16 CPUs

摘要

Looking to their next-generation designs, LSI and ARM faced a common problem: scaling beyond four or eight CPUs. LSI has developed several Axxia processors based on IBM's PowerPC 476FP, IBM's PLB6 coherent fabric, and a proprietary fabric connecting PLB6, accelerators, and DRAM memory interfaces. The 476FP and PLB6 scale to eight CPUs, but LSI wanted to shift to licensing ARM CPUs and to scale to even higher core counts. ARM has developed several multiprocessing-capable processors, beginning with the dual-core ARM11. Newer ARM CPUs, such as the Cortex-A15, support four-way clusters, and the CoreLink CCI-400 can join two of these clusters. The next step was to break the eight-CPU barrier and create a protocol that can scale to far more CPUs while supporting other performance enhancements. ARM must not only prepare a path for low-cost mobile processors to scale beyond today's designs but also enable high-end customers, like LSI, to integrate many ARM CPUs.