Installation

You can build NeoN by following these steps:

Clone the NeoN repository:

git clone https://github.com/exasim-project/NeoN.git

Navigate to the NeoN directory:

cd NeoN

NeoN uses CMake to build, thus the standard CMake procedure should work, however, we recommend using one of the provided CMake presets detailed below in Building with CMake Presets. From a build directory, you can execute:

mkdir build
cd build
cmake <DesiredBuildFlags> ..
cmake --build . -j<the number of CPU cores>
cmake --install .

By default, the command cmake –build . -j will use all the CPU cores available. It can consume a significant amount of memory when building with many cores. If you want to limit the number of cores used during the build step, you can specify the number of CPU cores as shown above.

The following can be chained with -D<DesiredBuildFlags>=<Value> to the CMake command. Most relevant build flags are:

Flag	Description	Default
CMAKE_BUILD_TYPE	Build in debug or release mode	Debug
NeoN_BUILD_DOC	Build NeoN with documentation	ON
NeoN_BUILD_TESTS	Build NeoN with tests	OFF

To browse the full list of build options it is recommended to use a build tool like ccmake. By opening the the project with cmake-gui you can easily set these flags and configure the build. NeoN specific build flags are prefixed by NeoN_.

Building for GPUs

NeoN will automatically enable Kokkos_ENABLE_CUDA or Kokkos_ENABLE_HIP if either of this is available on the system. This can be prevented by setting both options explicitly.

If NeoN does not detect the GPU backend automatically, you can set some relevant flags to enable GPU support during the configure step.

For NVIDIA GPUs, specifying the GPU architecture via CMAKE_CUDA_ARCHITECTURES should be sufficient.

-DCMAKE_CUDA_ARCHITECTURES=<GPU_ARCH>

For AMD GPUs, you may need to set up some relevant HIP environment variables before the configure step.

export PATH=/opt/rocm/bin:$PATH
export HIPCC_CXX=/usr/bin/g++  # If you want to use g++ as the host compiler

Then you can enable HIP during the configure step with the following flags.

-DCMAKE_CXX_COMPILER=hipcc
-DCMAKE_HIP_ARCHITECTURES=<GPU_ARCH>
-DKokkos_ARCH_AMD_<GPU_ARCH>=ON  # e.g., -DKokkos_ARCH_AMD_GFX90A=ON

After configuring for GPU support, you can continue to build NeoN.

Building with CMake Presets

Additionally, we provide several CMake presets to set commonly required flags if you compile NeoN in combination with Kokkos.

cmake --list-presets # To list existing presets

To build NeoN for production use, you can use the following commands:

cmake --preset production # To configure with ninja and common kokkos flags
cmake --build --preset production # To compile with ninja and common kokkos flags

It should be noted that the build directory changes depending on the chosen preset. This way you can have different build directories for different presets and easily switch between them.

Building with Spack

A good way to simplify the process of building NeoN is by using spack. Here is a short tutorial on how to build NeoN with spack for development. First clone spack from https://github.com/exasim-project/spack (until neon is fully merged into spack).

git clone https://github.com/exasim-project/spack -b neofoam
source spack/share/spack/setup-env.sh

Next we create a development environment for NeoN and add NeoN to it.

mkdir NeoN-env
spack env create  -d NeoN-env
spack env activate NeoN-env
cd NeoN-env
spack develop --path /home/greole/data/code/NeoN neon

Next we install clang 17 as a compiler into our environment

spack add llvm@17
spack install
spack compiler add "$(spack location -i llvm)"

Next, we add NeoN with the required dependencies.

spack add neon+test++cuda ^kokkos cuda_arch=80 cxxstd=20  ^ginkgo cuda_arch=80   %llvm@17
spack install

Prerequisites

The following tools are used in the development of this project:

required tools for documentation:

sudo apt install doxygen
pip install pre-commit sphinx furo breathe sphinx-sitemap

required tools for compilation (ubuntu latest 24.04):

sudo apt update
sudo apt install \
ninja-build \
clang-16 \
gcc-10 \
libomp-16-dev \
python3 \
python3-dev \
build-essential

Workflow with vscode

install the following extensions:

ms-vscode.cpptools
ms-vscode.cmake-tools

After installation, you can open the NeoN directory with vscode and configure the build with cmake presets with the cmake extension as shown below:

After configuring the build, you can build the project with the build button or test in “testing” tab (flask icon).

To create the documentation, you can use the ‘Build Sphinx Documentation’ task in the vscode task menu. Type Ctrl+P and type task and press space and the build documentation and press enter. The documentation will be created in the docs_build directory.