ppkMHD stands for Performance Portable Kokkos for Magneto-HydroDynamics (MHD) solvers.
Here a small list of numerical schemes implementations:
- second order MUSCL-HANCOCK scheme for hydrodynamics and MHD
- high-order MOOD (hydrodynamics only)
- high-order Spectral Difference Method schemes: hydrodynamics only
All scheme are available in 2D and 3D using Kokkos+MPI implementation, and support at least the OpenMP and CUDA kokkos backends (other backends may be used, but not tested).
- Kokkos library will either be built by ppkMHD by using cmake option
-DPPKMHD_BUILD_KOKKOS=ON, either be detected if you already have it installed. - cmake with version >= 3.X (3.X is chosen to meet Kokkos own requirement for cmake; i.e. it might increase in the future)
For beginner user, wu suggest that you build ppkMHD with -DPPKMHD_BUILD_KOKKOS=ON so that Kokkos is built together, with the same flags as the main application.
A few example builds, with minimal configuration options.
If you build kokkos yourself, we advise you to always active HWLOC TPLS.
Just make sure that your env variable CMAKE_PREFIX_PATH point to the location where Kokkos where installed. More precisely if Kokkos is installed in KOKKOS_ROOT, you add $KOKKOS_ROOT/lib/cmake to your CMAKE_PREFIX_PATH; this way kokkos will be found automagically by cmake, and the right Kokkos hardware backend will be selected.
# cd into ppkMHD toplevel sources
cmake -S . -B _build/default -DPPKMHD_BUILD_KOKKOS=OFF
cmake --build _build/default -j 6- Create a build directory, configure and make
# cd into ppkMHD toplevel sources
cmake -S . -B _build/openmp -DPPKMHD_BUILD_KOKKOS=ON -DPPKMHD_USE_MPI=OFF -DPPKMHD_BACKEND=OpenMP -DKokkos_ENABLE_HWLOC=ON
cmake --build _build/openmp -j 6Add variable CXX on the cmake command line to change the compiler (clang++, icpc, pgcc, ....).
- Create a build directory, configure and make
# cd into ppkMHD toplevel sources
cmake -S . -B _build/cuda -DPPKMHD_BUILD_KOKKOS=ON -DPPKMHD_USE_MPI=OFF -DPPKMHD_BACKEND=Cuda
# note: GPU architecture will be detected when building on a host with a GPU; if you're building on a host, and running on another machine
# you'll need to tell kokkos what is the target architecture, e.g. add flag like '-DKokkos_ARCH_TURING75=ON' on the cmake configure line
cmake --build _build/cuda -j 6Please make sure to use a CUDA-aware MPI implementation (OpenMPI or MVAPICH2) built with the proper flags for activating CUDA support.
It may happen that eventhough your MPI implementation is actually cuda-aware, cmake MPI detection (through a call to find_package(MPI) macro) may fails to detect if your MPI implementation is cuda aware. In that case, you can enforce cuda awareness by turning option PPKMHD_USE_MPI_CUDA_AWARE_ENFORCED to ON.
You don't need to use mpi compiler wrapper mpicxx, cmake should be able to correctly populate MPI_CXX_INCLUDE_PATH, MPI_CXX_LIBRARIES which are passed to all final targets by using the alias library MPI::MPI_CXX.
- Create a build directory, configure and make
mkdir build; cd build
cmake -DPPKMHD_USE_MPI=ON -DPPKMHD_BACKEND=Cuda -DKokkos_ARCH_TURING75=ON ..
make -j 4Example command line to run the application (1 GPU used per MPI task)
mpirun -np 4 ./ppkMHD ./test_implode_2D_mpi.iniIn order to activate building SDM (Spectral Difference Method) schemes, use cmake option -DPPKMHD_USE_SDM=ON.
The MOOD numerical scheme require some linear algebra (QR decomposition) on the host (not device). This is done using a Blas/Lapack implementation using the C language interface named Lapacke.
Please note that Atlas doesn't provide Lapackage. Currently (March 2017), on Ubuntu 16.04, package libatlas-dev is not compatible with package Lapacke (generate errors at link time). So please either Netlib/Lapack or OpenBLAS implementation.
If you want to enforce the use of OpenBLAS, just use a recent cmake (>=3.6) and add -DBLA_VENDOR on the cmake command line. This will tell the cmake build system (through the call to find_package(BLAS) ) to only look for the OpenBLAS implementation.
On a recent Ubuntu, if atlas is not installed, but OpenBLAS is, you don't need to have a bleeding edge cmake, current cmake will find OpenBLAS.
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