This repository is a work-in-progress GPU addon to the QMCkl library. It provides alternatives to the standard QMCkl functions to perform computations on GPU. The library is based on OpenMP offload and OpenACC, as to support a wide variety of compilers and targets combinations.
This readme contains configure, build and installation instructions, and redirects to dedicated files for usage instructions and the troubleshooting section.
The project uses GNU Autotools :
bash autogen.sh
./configure [arguments]
make
make install
The only other requirement for the library is a compiler toolchain that supports OpenMP or OpenACC offloading for your chosen target(s). The library is now completely standalone, and it can be linked without QMCkl CPU.
You can also check that offloading works on your system with the make check command.
Enabling either OpenMP and OpenACC is done at configure time, where (exactly) one of the two options has to be specified :
./configure --enable-[omp|acc]
In either case, the library interface is going to be exactly the same, as all of the OpenMP/OpenACC specific syntaxes are wrapped inside QMCkl GPU's functions.
Note: Using exactly one of those arguments is mandatory, as doing otherwise would result in an empty library. If none is specified, Autotools will throw a warning message and attempt to build the library with --enable-omp as a fallback solution.
We currently support nvc, gcc and clang. This means we have succesfully built and run the library with one of these compilers, on hardware from at least one vendor. You can specify which compiler to use by specifying the CC=... variable to the configure (gcc should be the default).
When specifying a known compiler, the configure also automatically tries to set the required flags to enable OpenMP or OpenACC offloading. In case the proposed flags don't work on your system, you can disable them whith the --disable-autoflags configure option. Then, simply specify correct compiler flags in the CFLAGS variable.
By default, QMCkl GPU will link with TREXIO, making it possible to initialize a GPU context by directly reading a TREXIO file. To disable this and skip the compilation of TREXIO related functions, use the --disable-trexio configure option.
See the dedicated USAGE.md file.
During the development and testing of the library, we encountered some compiler related issues. This section contains a list of known issues and fixes (if any).
See the dedicated TROUBLESHOOTING.md file.