ErikFabrizzi/NuSiF-Solver
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checkpoint 2D-omp: Improved performance

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This commit is contained in:
indiano 2025-05-05 18:23:01 +02:00
parent 5dd7f83dc5
commit 623b866f00
2 changed files with 72 additions and 64 deletions
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6
PoissonSolver/2D-omp/src/main.c
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@ -25,7 +25,6 @@ int main(int argc, char** argv)
Parameter params;
Solver solver;
initParameter(&params);
LIKWID_MARKER_INIT;
#pragma omp parallel
{
if (dummy == 1 || omp_get_thread_num() == 0)
@ -39,10 +38,11 @@ int main(int argc, char** argv)
readParameter(&params, argv[1]);
initSolver(&solver, &params, 2);
LIKWID_PROFILE("RB", solveRB);
startTime = getTimeStamp();
solveRB(&solver);
endTime = getTimeStamp();
printf(" %.2fs\n", endTime - startTime);
writeResult(&solver, "p.dat");
LIKWID_MARKER_CLOSE;
return EXIT_SUCCESS;
}

130
PoissonSolver/2D-omp/src/solver.c
View File

@ -116,87 +116,95 @@ void initSolver(Solver* solver, Parameter* params, int problem)
void solveRB(Solver* solver)
{
int imax = solver->imax;
int jmax = solver->jmax;
double eps = solver->eps;
int itermax = solver->itermax;
double dx2 = solver->dx * solver->dx;
double dy2 = solver->dy * solver->dy;
double idx2 = 1.0 / dx2;
double idy2 = 1.0 / dy2;
double factor = solver->omega * 0.5 * (dx2 * dy2) / (dx2 + dy2);
double* p = solver->p;
double* rhs = solver->rhs;
double epssq = eps * eps;
int it = 0;
double res = 1.0;
int dim[2] = { 0 };
int num_threads = 1;
const int imax = solver->imax;
const int jmax = solver->jmax;
const int itermax = solver->itermax;
const double epssq = solver->eps * solver->eps;
const double dx2 = solver->dx * solver->dx;
const double dy2 = solver->dy * solver->dy;
const double idx2 = 1.0 / dx2;
const double idy2 = 1.0 / dy2;
const double factor = solver->omega * 0.5 * (dx2 * dy2) / (dx2 + dy2);
double* __restrict p = solver->p;
double* __restrict rhs = solver->rhs;
int dim[2] = { 0 };
#pragma omp parallel
#pragma omp single
{
#pragma omp critical
num_threads = omp_get_num_threads();
omp_create_dim(omp_get_num_threads(), dim);
}
omp_create_dim(num_threads, dim);
printf("%d: { %d, %d}\n", num_threads, dim[0], dim[1]);
while ((res >= epssq) && (it < itermax)) {
#pragma omp parallel
double res = 0.0;
for (int it = 0; it < itermax; ++it) {
res = 0.0;
#pragma omp parallel reduction(+ : res)
{
res = 0.0;
int jsw, isw;
double local_res = 0.0;
int li_start = get_dim_start(get_x_choord(omp_get_thread_num(), dim),
dim[0],
solver->imax);
int lj_start = get_dim_start(get_y_choord(omp_get_thread_num(), dim),
dim[1],
solver->jmax);
int limax = li_start + distribute_dim(get_x_choord(omp_get_thread_num(), dim),
dim[0],
solver->imax);
int ljmax = lj_start + distribute_dim(get_y_choord(omp_get_thread_num(), dim),
dim[1],
solver->jmax);
jsw = ((li_start) % 2 == 0) == ((lj_start) % 2 == 0) ? 1 : 2;
for (int pass = 0; pass < 2; pass++) {
isw = jsw;
for (int i = li_start + 1; i < limax + 1; i++) {
const int tid = omp_get_thread_num();
const int li_start = get_dim_start(get_x_choord(tid, dim), dim[0], imax);
const int lj_start = get_dim_start(get_y_choord(tid, dim), dim[1], jmax);
const int limax = li_start +
distribute_dim(get_x_choord(tid, dim), dim[0], imax);
const int ljmax = lj_start +
distribute_dim(get_y_choord(tid, dim), dim[1], jmax);
int jsw = ((li_start) % 2 == 0) == ((lj_start) % 2 == 0) ? 1 : 2;
for (int pass = 0; pass < 2; ++pass) {
int isw = jsw;
for (int i = li_start + 1; i < limax + 1; ++i) {
for (int j = lj_start + isw; j < ljmax + 1; j += 2) {
double r = RHS(i, j) -
((P(i + 1, j) - 2.0 * P(i, j) + P(i - 1, j)) * idx2 +
(P(i, j + 1) - 2.0 * P(i, j) + P(i, j - 1)) *
idy2);
P(i, j) -= (factor * r);
res += (r * r);
P(i, j) -= factor * r;
res += r * r; /* reduction variable */
}
isw = 3 - isw;
}
#pragma omp barrier
jsw = 3 - jsw;
}
#pragma omp critical
{
res += local_res;
}
}
#pragma omp parallel for
for (int i = 1; i < imax + 1; i++) {
P(i, 0) = P(i, 1);
P(i, jmax + 1) = P(i, jmax);
}
#pragma omp parallel for
for (int j = 1; j < jmax + 1; j++) {
P(0, j) = P(1, j);
P(imax + 1, j) = P(imax, j);
}
if (lj_start == 0)
for (int i = li_start + 1; i < limax + 1; i++)
P(i, 0) = P(i, 1);
if (ljmax == jmax)
for (int i = li_start + 1; i < limax + 1; i++)
P(i, ljmax + 1) = P(i, ljmax);
if (li_start == 0)
for (int j = lj_start + 1; j < ljmax + 1; j++)
P(0, j) = P(1, j);
if (limax == imax)
for (int j = lj_start + 1; j < ljmax + 1; j++)
P(limax + 1, j) = P(limax, j);
}
res /= (double)(imax * jmax);
res = res / (double)(imax * jmax);
#ifdef DEBUG
printf("%d Residuum: %e\n", it, res);
#endif
it++;
if (res < epssq) {
printf("Solver took %d iterations to reach %e\n", it + 1, sqrt(res));
return;
}
}
printf("Solver took %d iterations to reach %f\n", it, sqrt(res));
printf("Solver reached itermax (%d) with residual %e\n", itermax, sqrt(res));
}
void writeResult(Solver* solver, char* filename)