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README.md

miniBUDE Kokkos

This is an implementation of miniBUDE using Kokkos.

Building

This implementation uses CMake. First, generate a build:

> cmake -Bbuild -H. -DCMAKE_BUILD_TYPE=Release

Flags:

  • CXX_EXTRA_FLAGS: STRING, appends extra flags that will be passed on to the compiler, applies to all configs
  • CXX_EXTRA_LINKER_FLAGS: STRING, appends extra linker flags (the comma separated list after the -Wl flag) to the linker; applies to all configs
  • KOKKOS_IN_TREE: STRING, use a specific Kokkos source directory for an in-tree build where Kokkos and the project is compiled together.
    • FORWARD_CXX_EXTRA_FLAGS_TO_KOKKOS : ON|OFF, whether to forward CXX_EXTRA_FLAGS when building Kokkos. This is OFF by default as Kokkos has a set of tested flags for each compiler.
  • Kokkos_ROOT: STRING, path to the local Kokkos installation, this is optional and mutually exclusive with KOKKOS_IN_TREE.
  • DEFAULT_WGSIZE: INGEGER, sets the block size. Defaults to 64.
  • CUSTOM_SYSTEM_INCLUDE_FLAG, sets the prefix flag for including system libraries. For example, setting this flag to -I replaces all -isystem <headers...> with -I <headers...>.

Compilers can be specified via the usual CMake options, for example:

> cmake -Bbuild -H.  \
    -DCMAKE_C_COMPILER=/nfs/software/x86_64/gcc/9.1.0/bin/gcc \
    -DCMAKE_CXX_COMPILER=/nfs/software/x86_64/gcc/9.1.0/bin/g++ \
    -DCMAKE_BUILD_TYPE=Release

IMPORTANT: If need to specify Kokkos flags at build-time, you must use the KOKKOS_IN_TREE option. For example:

> cmake -Bbuild -H.  \
    -DKOKKOS_IN_TREE=<path_to_kokkos_src> \
    -DKokkos_ENABLE_OPENMP=ON \
    -DKokkos_ARCH_ZEN2=ON \
    -DKokkos_ENABLE_AGGRESSIVE_VECTORIZATION=ON \
    -DCMAKE_BUILD_TYPE=Release

Proceed with compiling:

> cmake --build build --target bude --config Release -j $(nproc)

The binary can be found at build/bude.

Block Sizes

This implementation includes a tunable block size similar to OpenCL workgroups. The default value is 64, which is suitable for 512-bit vectors, e.g. in Skylake or A64FX, but higher values may sometimes be beneficial. For 128-bit vectors, 16 is a good choice.

Running

This implementation has no special run-time options. The -n and -i parameters are available. Run bude -h for a help message.