Setup¶

This page is intended as a guide to jump start new KokkosComm users.

System requirements¶

Name	Requirement
CMake	3.25+
C++ compiler	Conforming to ISO C++20 standard
Kokkos	4.7+
MPI	Conforming to MPI-3+ standard
NCCL	2+

KokkosComm will attempt to support the same systems and toolchains as Kokkos.

Installation¶

Download¶

KokkosComm’s source code is available on GitHub, which you can obtain using the following command:

$ git clone https://github.com/kokkos/kokkos-comm.git

Or using the GitHub CLI tool:

$ gh repo clone kokkos/kokkos-comm

Build¶

A basic configure and build of KokkosComm:

$ cmake -B <BUILD_DIR> -DKokkos_ROOT=<KOKKOS_INSTALL_DIR>
$ cmake --build <BUILD_DIR>

Test¶

$ cmake -B <BUILD_DIR> \
        -DKokkos_ROOT=<KOKKOS_INSTALL_DIR> \
        -DKokkosComm_ENABLE_TESTS=ON
$ cmake --build <BUILD_DIR>
$ ctest --test-dir <BUILD_DIR>/unit_tests

For a detailed guide on testing KokkosComm, please refer to the Testing section.

Install¶

$ cmake --install <BUILD_DIR> --prefix <INSTALL_DIR>

Integration in user applications¶

Similarly to Kokkos, KokkosComm is packaged with a modern CMake build system.

Once installed, you can declare KokkosComm as a dependency of your project by adding the following line to your CMakeLists.txt:

find_package(KokkosComm REQUIRED)

Then, for every executable or library in your project that depends on KokkosComm:

target_link_libraries(MyTarget KokkosComm::KokkosComm)

CMake configuration options¶

This section lists the available options to customize your KokkosComm build/installation.

Important

All KokkosComm CMake options are prefixed with KokkosComm_, which is case-sensitive.

Communication backend selection¶

You can enable communication backends by configuring with -DKokkosComm_ENABLE_<COMM_BACKEND>=ON, where <COMM_BACKEND> is replaced with the specific communication backend you want to enable (e.g. -DKokkosComm_ENABLE_MPI=ON for MPI).

CMake option	Default	Description
`KokkosComm_ENABLE_MPI`	`ON`	Build with MPI backend.
`KokkosComm_ENABLE_NCCL`	`OFF`	Build with NCCL backend (experimental).

Behavior tuning¶

CMake option	Default	Description
`KokkosComm_ABORT_ON_ERROR`	`OFF`	Runtime check failures trigger a global abort.

General options¶

CMake option	Default	Description
`KokkosComm_ENABLE_TESTS`	`OFF`	Build unit tests.
`KokkosComm_ENABLE_PERFTESTS`	`OFF`	Build performance tests.
`KokkosComm_INSTALL_CMAKE_PACKAGE`	`${PROJECT_IS_TOP_LEVEL}`	Install a CMake config-file package together with the library. Defaults to `ON` for standalone builds, `OFF` otherwise. Note that library files are always installed.

Known quirks¶

At Sandia, with the VPN enabled while using MPICH, you may have to do the following:

$ export FI_PROVIDER=tcp