The GridTools framework is a set of libraries and utilities to develop performance portable applications in the area of weather and climate. To achieve the goal of performance portability, the user-code is written in a generic form which is then optimized for a given architecture at compile-time. The core of GridTools is the stencil composition module which implements a DSL embedded in C++ for stencils and stencil-like patterns. Further, GridTools provides modules for halo exchanges, boundary conditions, data management and bindings to C and Fortran.

GridTools is successfully used to accelerate the dynamical core of the COSMO model with improved performance on CUDA-GPUs compared to the current official version, demonstrating production quality and feature-completeness of the library for models on lat-lon grids. The GridTools-based dynamical core is shipped with COSMO v5.7 and later, see release notes COSMO v5.7.

Although GridTools was developed for weather and climate applications it might be applicable for other domains with a focus on stencil-like computations.

A detailed introduction can be found in the documentation.

Installation instructions

git clone https://github.com/GridTools/gridtools.git cd gridtools mkdir -p build && cd build cmake .. make -j8 make test

For choosing the compiler, use the standard CMake techniques, e.g. setting the environment variables CXX=`which g++` # full path to the C++ compiler CC=`which gcc` # full path to theC compiler FC=`which gfortran` # full path to theFortran compiler CUDACXX=`which nvcc` # full path to NVCC CUDAHOSTCXX=`which g++` # full path to the C++ compiler to be used as CUDA host compiler

Requirements

• C++17 compiler (see also list of tested compilers)
• CMake (3.21.0 or later)
• CUDA Toolkit (11.0 or later, optional)
• MPI (optional, CUDA-aware MPI for the GPU communication module gcl_gpu)

Supported compilers

The GridTools libraries are currently nightly tested with the following compilers on CSCS supercomputers.

| Compiler | Backend | Tested on | Comments | | --- | --- | --- | --- | | Cray clang version 12.0.3 | all backends | Piz Daint | P100 GPU | with Clang-CUDA | Cray clang version 10.0.2 + NVCC 11.2 | all backends | Piz Daint | P100 GPU | | Cray clang version 12.0.3 | all backends | Piz Daint | with -std=c++20 | GNU 11.2.0 + NVCC 11.0 | all backends | Piz Daint | P100 GPU | | GNU 11.2.0 + NVCC 11.2 | all backends | Dom | P100 GPU | | GNU 8.3.0 + NVCC 11.2 | all backends | Tsa | V100 GPU |

Known issues

• CUDA 11.0.x has a severe issue, see https://github.com/GridTools/gridtools/issues/1522. Under certain conditions, GridTools code will not compile for this version of CUDA. CUDA 11.1.x and later should not be affected by this issue.
• CUDA 12.1, 12.2, 12.3, 12.4 have various issues related to constexpr, see https://github.com/GridTools/gridtools/issues/1766. We recommend CUDA 12.5 or later.
• Cray Clang version 11.0.0 has a problem with the gridtools::tuple conversion constructor, see https://github.com/GridTools/gridtools/issues/1615.

Partly supported (expected to work, but not tested regularly)

| Compiler | Backend | Date | Comments | | --- | --- | --- | --- | | Intel 19.1.1.217 | all backends | 2021-09-30 | with cmake . -DCMAKE_CXX_FLAGS=-qnextgen | | NVHPC 23.3 | all backends | 2023-04-20 | only compilation is tested regularly in CI | | ROCm 6.0.3 | all backends | 2024-09-24 | tested on AMD MI250X (LUMI) |

Contributing

Contributions to the GridTools framework are welcome. Please open an issue for any bugs that you encounter or provide a fix or enhancement as a PR. External contributions to GridTools require us a signed copy of a copyright release form to ETH Zurich. We will contact you on the PR.