unimore/hpc-2022-g3
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init_array: Do not optimize, costs are greater than benefits

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Steffo 2022-11-15 19:46:23 +01:00
parent 7ae893d977
commit f48d351890
Signed by: steffo
GPG key ID: 6965406171929D01
1 changed files with 7 additions and 4 deletions
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11
OpenMP/linear-algebra/kernels/atax/atax.c
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@ -24,11 +24,14 @@ static void init_array(int nx, int ny,
{ {
int i, j; int i, j;
// TODO: Optimizable loop, every task has no dependencies on the other ones // Parallelizing this causes a slowdown, as the cost of context-switches is greater than the cost of inlline execution
for (i = 0; i < ny; i++) // #pragma omp parallel for num_threads(SOMETHING) schedule(static)
for (i = 0; i < ny; i++) {
x[i] = i * M_PI; x[i] = i * M_PI;
}
// TODO: Optimizable loop, every task has no dependencies on the other ones // Same here, but many times more
// #pragma omp parallel for num_threads(SOMETHING) schedule(static)
for (i = 0; i < nx; i++) for (i = 0; i < nx; i++)
for (j = 0; j < ny; j++) for (j = 0; j < ny; j++)
A[i][j] = ((DATA_TYPE)i * (j + 1)) / nx; A[i][j] = ((DATA_TYPE)i * (j + 1)) / nx;
@ -113,7 +116,7 @@ int main(int argc, char **argv)
/* Prevent dead-code elimination. All live-out data must be printed /* Prevent dead-code elimination. All live-out data must be printed
by the function call in argument. */ by the function call in argument. */
polybench_prevent_dce(print_array(nx, POLYBENCH_ARRAY(y))); polybench_prevent_dce(print_array(nx, POLYBENCH_ARRAY(y)));
/* Be clean. */ /* Be clean. */
POLYBENCH_FREE_ARRAY(A); POLYBENCH_FREE_ARRAY(A);
POLYBENCH_FREE_ARRAY(x); POLYBENCH_FREE_ARRAY(x);