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Additional tests for hybrid MPI + OpenMP for loop parallelization #28

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Apr 15, 2025
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Additional tests for hybrid MPI + OpenMP for loop parallelization #28

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50 changes: 50 additions & 0 deletions test/c++/mpi_chunk.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -67,4 +67,54 @@ TEST(MPI, OMPHybrid) {
EXPECT_EQ(n * (n - 1) / 2, sum);
}

TEST(MPI, OMPHybridParallelForSingleLoop) {
// first divide a range among MPI processes and then among OMP threads
mpi::communicator world;
int const n = 10;
long sum = 0;
#pragma omp parallel for reduction(+ : sum)
for (auto i : mpi::chunk(range(n))) sum += i;

// reduce and check the sum, i.e. that every element of the range has been visited
sum = mpi::all_reduce(sum, world);
EXPECT_EQ(n * (n - 1) / 2, sum);
}

TEST(MPI, OMPHybridParallelForDoubleLoop) {
mpi::communicator world;
int const n1 = 11;
int const n2 = 13;

// divide the outer loop among MPI processes, collapse the inner and outer loop and divide it among OMP threads
long sum = 0;
#pragma omp parallel for collapse(2) reduction(+ : sum)
for (auto i : mpi::chunk(range(n1))) {
for (auto j : range(n2)) sum += i * n2 + j;
}

// reduce and check the sum, i.e. that every element of the range has been visited
sum = mpi::all_reduce(sum, world);
EXPECT_EQ(n1 * n2 * (n1 * n2 - 1) / 2, sum);
}

TEST(MPI, OMPHybridParallelForTripleLoop) {
mpi::communicator world;
int const n1 = 11;
int const n2 = 13;
int const n3 = 17;

// divide the outer loop among MPI processes, collapse the inner and outer loops and divide it among OMP threads
long sum = 0;
#pragma omp parallel for collapse(3) reduction(+ : sum)
for (auto i : mpi::chunk(range(n1))) {
for (auto j : range(n2)) {
for (auto k : range(n3)) sum += i * n2 * n3 + j * n3 + k;
}
}

// reduce and check the sum, i.e. that every element of the range has been visited
sum = mpi::all_reduce(sum, world);
EXPECT_EQ(n1 * n2 * n3 * (n1 * n2 * n3 - 1) / 2, sum);
}

MPI_TEST_MAIN;
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