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fix: 2D-mpi was saving data incorrectly, showing discontinuity in plot

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This commit is contained in:
Erik Fabrizzi 2025-04-28 18:38:09 +02:00
parent 92e9ed764f
commit 765883ab88
1 changed files with 388 additions and 396 deletions
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96
PoissonSolver/2D-mpi/src/solver.c
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@ -17,17 +17,16 @@
#define P(i, j) p[(j) * (imax + 2) + (i)] #define P(i, j) p[(j) * (imax + 2) + (i)]
#define RHS(i, j) rhs[(j) * (imax + 2) + (i)] #define RHS(i, j) rhs[(j) * (imax + 2) + (i)]
static int sizeOfRank(int rank, int size, int N) static int sizeOfRank(int rank, int size, int N) {
{
return N / size + ((N % size > rank) ? 1 : 0); return N / size + ((N % size > rank) ? 1 : 0);
} }
static void print(Solver* solver) static void print(Solver *solver) {
{
double *p = solver->p; double *p = solver->p;
int imax = solver->imax; int imax = solver->imax;
printf("### RANK %d #######################################################\n", printf(
"### RANK %d #######################################################\n",
solver->rank); solver->rank);
for (int j = 0; j < solver->jmaxLocal + 2; j++) { for (int j = 0; j < solver->jmaxLocal + 2; j++) {
printf("%02d: ", j); printf("%02d: ", j);
@ -39,12 +38,9 @@ static void print(Solver* solver)
fflush(stdout); fflush(stdout);
} }
static void exchange(Solver* solver) static void exchange(Solver *solver) {
{ MPI_Request requests[4] = {MPI_REQUEST_NULL, MPI_REQUEST_NULL,
MPI_Request requests[4] = { MPI_REQUEST_NULL, MPI_REQUEST_NULL, MPI_REQUEST_NULL};
MPI_REQUEST_NULL,
MPI_REQUEST_NULL,
MPI_REQUEST_NULL };
/* exchange ghost cells with top neighbor */ /* exchange ghost cells with top neighbor */
if (solver->rank + 1 < solver->size) { if (solver->rank + 1 < solver->size) {
@ -52,8 +48,10 @@ static void exchange(Solver* solver)
double *src = solver->p + (solver->jmaxLocal) * (solver->imax + 2) + 1; double *src = solver->p + (solver->jmaxLocal) * (solver->imax + 2) + 1;
double *dst = solver->p + (solver->jmaxLocal + 1) * (solver->imax + 2) + 1; double *dst = solver->p + (solver->jmaxLocal + 1) * (solver->imax + 2) + 1;
MPI_Isend(src, solver->imax, MPI_DOUBLE, top, 1, MPI_COMM_WORLD, &requests[0]); MPI_Isend(src, solver->imax, MPI_DOUBLE, top, 1, MPI_COMM_WORLD,
MPI_Irecv(dst, solver->imax, MPI_DOUBLE, top, 2, MPI_COMM_WORLD, &requests[1]); &requests[0]);
MPI_Irecv(dst, solver->imax, MPI_DOUBLE, top, 2, MPI_COMM_WORLD,
&requests[1]);
} }
/* exchange ghost cells with bottom neighbor */ /* exchange ghost cells with bottom neighbor */
@ -62,61 +60,58 @@ static void exchange(Solver* solver)
double *src = solver->p + (solver->imax + 2) + 1; double *src = solver->p + (solver->imax + 2) + 1;
double *dst = solver->p + 1; double *dst = solver->p + 1;
MPI_Isend(src, solver->imax, MPI_DOUBLE, bottom, 2, MPI_COMM_WORLD, &requests[2]); MPI_Isend(src, solver->imax, MPI_DOUBLE, bottom, 2, MPI_COMM_WORLD,
MPI_Irecv(dst, solver->imax, MPI_DOUBLE, bottom, 1, MPI_COMM_WORLD, &requests[3]); &requests[2]);
MPI_Irecv(dst, solver->imax, MPI_DOUBLE, bottom, 1, MPI_COMM_WORLD,
&requests[3]);
} }
MPI_Waitall(4, requests, MPI_STATUSES_IGNORE); MPI_Waitall(4, requests, MPI_STATUSES_IGNORE);
} }
void getResult(Solver* solver) void getResult(Solver *solver) {
{
double *Pall = NULL; double *Pall = NULL;
int *rcvCounts, *displs; int *rcvCounts, *displs;
if (solver->rank == 0) { if (solver->rank == 0) {
Pall = allocate(64, (solver->imax + 2) * (solver->jmax + 2) * sizeof(double)); Pall =
allocate(64, (solver->imax + 2) * (solver->jmax + 2) * sizeof(double));
rcvCounts = (int *)malloc(solver->size * sizeof(int)); rcvCounts = (int *)malloc(solver->size * sizeof(int));
displs = (int *)malloc(solver->size * sizeof(int)); displs = (int *)malloc(solver->size * sizeof(int));
rcvCounts[0] = solver->jmaxLocal * (solver->imax + 2); rcvCounts[0] = (solver->jmaxLocal + 1) * (solver->imax + 2);
displs[0] = 0; displs[0] = 0;
int cursor = rcvCounts[0]; int cursor = rcvCounts[0];
for (int i = 1; i < solver->size; i++) { for (int i = 1; i < solver->size; i++) {
rcvCounts[i] = sizeOfRank(i, solver->size, solver->jmax) * (solver->imax + 2); rcvCounts[i] =
sizeOfRank(i, solver->size, solver->jmax) * (solver->imax + 2);
displs[i] = cursor; displs[i] = cursor;
cursor += rcvCounts[i]; cursor += rcvCounts[i];
} }
rcvCounts[solver->size - 1] =
(sizeOfRank(solver->size - 1, solver->size, solver->jmax)+1) *
(solver->imax + 2);
} }
int cnt = solver->jmaxLocal * (solver->imax + 2); int cnt = solver->jmaxLocal * (solver->imax + 2);
double *sendbuffer = solver->p + (solver->imax + 2); double *sendbuffer = solver->p + (solver->imax + 2);
MPI_Gatherv(sendbuffer, if(solver->rank == 0 || solver->rank == solver->size-1) cnt= (solver->jmaxLocal+1)*(solver->imax+2);
cnt, if(solver->rank == 0) sendbuffer = solver->p;
MPI_DOUBLE, MPI_Gatherv(sendbuffer, cnt, MPI_DOUBLE, Pall, rcvCounts, displs, MPI_DOUBLE,
Pall, 0, MPI_COMM_WORLD);
rcvCounts,
displs,
MPI_DOUBLE,
0,
MPI_COMM_WORLD);
if (solver->rank == 0) { if (solver->rank == 0) {
writeResult(solver, Pall, "p.dat"); writeResult(solver, Pall, "p.dat");
} }
} }
void initSolver(Solver* solver, Parameter* params, int problem) void initSolver(Solver *solver, Parameter *params, int problem) {
{
MPI_Comm_rank(MPI_COMM_WORLD, &(solver->rank)); MPI_Comm_rank(MPI_COMM_WORLD, &(solver->rank));
MPI_Comm_size(MPI_COMM_WORLD, &(solver->size)); MPI_Comm_size(MPI_COMM_WORLD, &(solver->size));
solver->imax = params->imax; solver->imax = params->imax;
solver->jmax = params->jmax; solver->jmax = params->jmax;
solver->jmaxLocal = sizeOfRank(solver->rank, solver->size, solver->jmax); solver->jmaxLocal = sizeOfRank(solver->rank, solver->size, solver->jmax);
printf("RANK %d: imaxLocal : %d, jmaxLocal : %d\n", printf("RANK %d: imaxLocal : %d, jmaxLocal : %d\n", solver->rank,
solver->rank, solver->imax, solver->jmaxLocal);
solver->imax,
solver->jmaxLocal);
solver->dx = params->xlength / params->imax; solver->dx = params->xlength / params->imax;
solver->dy = params->ylength / params->jmax; solver->dy = params->ylength / params->jmax;
@ -158,8 +153,7 @@ void initSolver(Solver* solver, Parameter* params, int problem)
} }
} }
void debug(Solver* solver) void debug(Solver *solver) {
{
int imax = solver->imax; int imax = solver->imax;
int rank = solver->rank; int rank = solver->rank;
double *p = solver->p; double *p = solver->p;
@ -178,9 +172,11 @@ void debug(Solver* solver)
/* } */ /* } */
/* if ( rank == 0 ) { */ /* if ( rank == 0 ) { */
/* printf("##########################################################\n"); */ /* printf("##########################################################\n");
*/
/* printf("## Exchange ghost layers\n"); */ /* printf("## Exchange ghost layers\n"); */
/* printf("##########################################################\n"); */ /* printf("##########################################################\n");
*/
/* } */ /* } */
/* exchange(solver); */ /* exchange(solver); */
@ -192,8 +188,7 @@ void debug(Solver* solver)
} }
} }
int solve(Solver* solver) int solve(Solver *solver) {
{
double r; double r;
int it = 0; int it = 0;
double res, res1; double res, res1;
@ -269,8 +264,7 @@ int solve(Solver* solver)
} }
} }
int solveRB(Solver* solver) int solveRB(Solver *solver) {
{
double r; double r;
int it = 0; int it = 0;
double res, res1; double res, res1;
@ -305,8 +299,8 @@ int solveRB(Solver* solver)
for (int j = 1; j < jmaxLocal + 1; j++) { for (int j = 1; j < jmaxLocal + 1; j++) {
for (int i = isw; i < imax + 1; i += 2) { for (int i = isw; i < imax + 1; i += 2) {
double r = RHS(i, j) - double r =
((P(i + 1, j) - 2.0 * P(i, j) + P(i - 1, j)) * idx2 + 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 + 1) - 2.0 * P(i, j) + P(i, j - 1)) * idy2);
P(i, j) -= (factor * r); P(i, j) -= (factor * r);
@ -345,8 +339,7 @@ int solveRB(Solver* solver)
} }
} }
int solveRBA(Solver* solver) int solveRBA(Solver *solver) {
{
double r; double r;
int it = 0; int it = 0;
double res; double res;
@ -382,8 +375,8 @@ int solveRBA(Solver* solver)
for (int j = 1; j < jmaxLocal + 1; j++) { for (int j = 1; j < jmaxLocal + 1; j++) {
for (int i = isw; i < imax + 1; i += 2) { for (int i = isw; i < imax + 1; i += 2) {
double r = RHS(i, j) - double r =
((P(i + 1, j) - 2.0 * P(i, j) + P(i - 1, j)) * idx2 + 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 + 1) - 2.0 * P(i, j) + P(i, j - 1)) * idy2);
P(i, j) -= (omega * factor * r); P(i, j) -= (omega * factor * r);
@ -417,8 +410,7 @@ int solveRBA(Solver* solver)
printf("Solver took %d iterations to reach %f\n", it, sqrt(res)); printf("Solver took %d iterations to reach %f\n", it, sqrt(res));
} }
void writeResult(Solver* solver, double* m, char* filename) void writeResult(Solver *solver, double *m, char *filename) {
{
int imax = solver->imax; int imax = solver->imax;
int jmax = solver->jmax; int jmax = solver->jmax;
double *p = solver->p; double *p = solver->p;