Skip to content


Switch branches/tags
This branch is 1 commit ahead, 4019 commits behind openucx:master.

Latest commit



Failed to load latest commit information.
Latest commit message
Commit time

Unified Communication X

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 for inter-node communication, and shared memory mechanisms for efficient intra-node communication.

Using UCX

Release Builds

Building UCX is typically a combination of running "configure" and "make". Execute the following commands to install the UCX system from within the directory at the top of the tree:

$ ./
$ ./contrib/configure-release --prefix=/where/to/install
$ make -j8
$ make install

NOTE: Compiling support for various networks or other specific hardware may require additional command line flags when running configure.

Developer Builds

$ ./
$ ./contrib/configure-devel --prefix=$PWD/install-debug

*** NOTE: Developer builds of UCX typically include a large performance penalty at run-time because of extra debugging code.

Running internal unit tests

$ make -C test/gtest test

Build RPM package

$ contrib/ -s -b

Build DEB package

$ dpkg-buildpackage -us -uc

Build Doxygen documentation

$ make docs

OpenMPI and OpenSHMEM installation with UCX

Wiki page

MPICH installation with UCX

Wiki page

UCX Performance Test

Start server:

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

Connect client:

$ ./src/tools/perf/ucx_perftest <server-hostname> -t tag_lat -c 1

Note: the -c flag sets CPU affinity. If running both commands on same host, make sure you set the affinity to different CPU cores.

Our Community


UCX is licensed as:

Contributor Agreement and Guidelines

In order to contribute to UCX, please sign up with an appropriate Contributor Agreement.

Follow these instructions when submitting contributions and changes.

UCX Publications

To reference UCX in a publication, please use the following entry:

  title={UCX: an open source framework for HPC network APIs and beyond},
  author={Shamis, Pavel and Venkata, Manjunath Gorentla and Lopez, M Graham and Baker, Matthew B and Hernandez, Oscar and Itigin, Yossi and Dubman, Mike and Shainer, Gilad and Graham, Richard L and Liss, Liran and others},
  booktitle={2015 IEEE 23rd Annual Symposium on High-Performance Interconnects},

To reference the UCX website:

    title = {{The Unified Communication X Library}},
    key = {{{The Unified Communication X Library}},
    howpublished = {{\url{}}}

UCX Architecture

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

Supported Transports

Supported CPU Architectures


Unified Communication X (mailing list -







No packages published


  • C 60.0%
  • C++ 35.8%
  • M4 1.4%
  • Java 1.4%
  • Shell 0.7%
  • Makefile 0.5%
  • Other 0.2%