UPI is a low-latency coherent interconnect for scalable multiprocessor systems with a shared address space.
It uses a directory-based home snoop coherency protocol with a transfer speed of up to 10.4 GT/s.
A combined caching and home agent (CHA) handles resolution of coherency across multiple processors, as well as snoop requests from processor cores and local and remote agents.
Separate physical CHAs are placed within each processor core and last level cache (LLC) bank to improve scalability according to the number of cores, memory controllers, or the sub-NUMA clustering mode.
The address space is interleaved across different CHAs, which act like a single logical agent.