UCX stands for Unified Communication X. UCX provides an optimized communication layer for Message Passing (MPI), PGAS/OpenSHMEM libraries and RPC/data-centric applications. UCX utilizes high-speed networks, such as RDMA (InfiniBand, RoCE, etc), Cray Gemini or Aries, for inter-node communication. If no such network is available, TCP is used instead. UCX supports efficient transfer of data in either main memory (RAM) or GPU memory (through CUDA and RoCM libraries). In addition, UCX provides efficient intra-node communication, by leveraging the following shared memory mechanisms: posix, sysv, cma, knem, and xpmem.

Running internal unit tests

$ ./autogen.sh
$ ./contrib/configure-devel
$ make
$ make -C test/gtest test

Running UCX hello-world

Compile:

$ ./autogen.sh  
$ ./contrib/configure-release --prefix=$PWD/install
$ make

Start server:

$ ./src/tools/perf/ucx_perftest -c 0

Connect client:

$ ./src/tools/perf/ucx_perftest <server-hostname> -t tag_lat -c 0

UCX high-level layout

UCX contains four main components:

• UCP - UCX Protocol. Implements high-level abstractions such as tag-matching, streams, connection negotiation and establishment, multi-rail, and handling different memory types.
• UCT - UCX Transport. Implements low-level communication primitives such as active messages, remote memory access, and atomic operations.
• UCS - UCX Services. A collection of data structures, algorithms, and system utilities for common use.
• UCM - UCX Memory. Intercepts memory allocation and release events, used by memory registration cache.