Setup¶

This page is intended as a guide to jump start new Kokkos Comm 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+

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

Installation¶

Download¶

Kokkos Comm’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:

$ gh repo clone kokkos/kokkos-comm

Build¶

A basic configure and build of Kokkos Comm:

$ 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 Kokkos Comm, please refer to the Testing section.

Install¶

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

Integration in user applications¶

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

Once installed, you can declare Kokkos Comm 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 Kokkos Comm:

target_link_libraries(MyTarget KokkosComm::KokkosComm)

CMake configuration options¶

This section lists the available options to customize your Kokkos Comm build and/or installation.

Important

All Kokkos Comm 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