2.3. Simple Kokkos Example

The Kokkos C++ library provides data layout and location information to the compiler by enriching the type system.

For example an N**x**3 array on the GPU could be declared using:

#include <iostream>
#include <mpi.h>
#include <Kokkos_Core.hpp>

using namespace Kokkos;

typedef View<double *[3],LayoutLeft,CudaSpace> t_crd;

class RunCross {
    public:
        RunCross(const t_crd &a_,
                 const t_crd &b_,
                 const t_crd &c_) : a(a_), b(b_), c(c_) {};
        typedef int size_type;
        KOKKOS_INLINE_FUNCTION void operator()(const size_type i) const {
            c(i,0) = a(i,1)*b(i,2)-a(i,2)*b(i,1);
            c(i,1) = a(i,2)*b(i,0)-a(i,0)*b(i,2);
            c(i,2) = a(i,0)*b(i,1)-a(i,1)*b(i,0);
        }

    private:
        t_crd a, b, c;
};

int run(int N) {
    t_crd a("A", N);
    t_crd b("B", N);
    t_crd c("C", N);

    parallel_for(N, RunCross(a, b, c));

    return 0;
}

int main(int argc, char *argv[]) {
    int n = -1;

    MPI_Init(&argc, &argv);
    Kokkos::initialize(argc, argv);
    n = run(10000);
    Kokkos::finalize();
    MPI_Finalize();
    return n;
}

TODO:

• Compiling instructions