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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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136
PoissonSolver/2D-mpi/src/solver.c
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@ -17,17 +17,16 @@
#define P(i, j) p[(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);
}
static void print(Solver* solver)
{
double* p = solver->p;
static void print(Solver *solver) {
double *p = solver->p;
int imax = solver->imax;
printf("### RANK %d #######################################################\n",
printf(
"### RANK %d #######################################################\n",
solver->rank);
for (int j = 0; j < solver->jmaxLocal + 2; j++) {
printf("%02d: ", j);
@ -39,84 +38,80 @@ static void print(Solver* solver)
fflush(stdout);
}
static void exchange(Solver* solver)
{
MPI_Request requests[4] = { MPI_REQUEST_NULL,
MPI_REQUEST_NULL,
MPI_REQUEST_NULL,
MPI_REQUEST_NULL };
static void exchange(Solver *solver) {
MPI_Request requests[4] = {MPI_REQUEST_NULL, MPI_REQUEST_NULL,
MPI_REQUEST_NULL, MPI_REQUEST_NULL};
/* exchange ghost cells with top neighbor */
if (solver->rank + 1 < solver->size) {
int top = solver->rank + 1;
double* src = solver->p + (solver->jmaxLocal) * (solver->imax + 2) + 1;
double* dst = solver->p + (solver->jmaxLocal + 1) * (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;
MPI_Isend(src, solver->imax, MPI_DOUBLE, top, 1, MPI_COMM_WORLD, &requests[0]);
MPI_Irecv(dst, solver->imax, MPI_DOUBLE, top, 2, MPI_COMM_WORLD, &requests[1]);
MPI_Isend(src, solver->imax, MPI_DOUBLE, top, 1, MPI_COMM_WORLD,
&requests[0]);
MPI_Irecv(dst, solver->imax, MPI_DOUBLE, top, 2, MPI_COMM_WORLD,
&requests[1]);
}
/* exchange ghost cells with bottom neighbor */
if (solver->rank > 0) {
int bottom = solver->rank - 1;
double* src = solver->p + (solver->imax + 2) + 1;
double* dst = solver->p + 1;
double *src = solver->p + (solver->imax + 2) + 1;
double *dst = solver->p + 1;
MPI_Isend(src, solver->imax, MPI_DOUBLE, bottom, 2, MPI_COMM_WORLD, &requests[2]);
MPI_Irecv(dst, solver->imax, MPI_DOUBLE, bottom, 1, MPI_COMM_WORLD, &requests[3]);
MPI_Isend(src, solver->imax, MPI_DOUBLE, bottom, 2, MPI_COMM_WORLD,
&requests[2]);
MPI_Irecv(dst, solver->imax, MPI_DOUBLE, bottom, 1, MPI_COMM_WORLD,
&requests[3]);
}
MPI_Waitall(4, requests, MPI_STATUSES_IGNORE);
}
void getResult(Solver* solver)
{
double* Pall = NULL;
void getResult(Solver *solver) {
double *Pall = NULL;
int *rcvCounts, *displs;
if (solver->rank == 0) {
Pall = allocate(64, (solver->imax + 2) * (solver->jmax + 2) * sizeof(double));
rcvCounts = (int*)malloc(solver->size * sizeof(int));
displs = (int*)malloc(solver->size * sizeof(int));
rcvCounts[0] = solver->jmaxLocal * (solver->imax + 2);
Pall =
allocate(64, (solver->imax + 2) * (solver->jmax + 2) * sizeof(double));
rcvCounts = (int *)malloc(solver->size * sizeof(int));
displs = (int *)malloc(solver->size * sizeof(int));
rcvCounts[0] = (solver->jmaxLocal + 1) * (solver->imax + 2);
displs[0] = 0;
int cursor = rcvCounts[0];
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;
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);
double* sendbuffer = solver->p + (solver->imax + 2);
MPI_Gatherv(sendbuffer,
cnt,
MPI_DOUBLE,
Pall,
rcvCounts,
displs,
MPI_DOUBLE,
0,
MPI_COMM_WORLD);
double *sendbuffer = solver->p + (solver->imax + 2);
if(solver->rank == 0 || solver->rank == solver->size-1) cnt= (solver->jmaxLocal+1)*(solver->imax+2);
if(solver->rank == 0) sendbuffer = solver->p;
MPI_Gatherv(sendbuffer, cnt, MPI_DOUBLE, Pall, rcvCounts, displs, MPI_DOUBLE,
0, MPI_COMM_WORLD);
if (solver->rank == 0) {
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_size(MPI_COMM_WORLD, &(solver->size));
solver->imax = params->imax;
solver->jmax = params->jmax;
solver->jmaxLocal = sizeOfRank(solver->rank, solver->size, solver->jmax);
printf("RANK %d: imaxLocal : %d, jmaxLocal : %d\n",
solver->rank,
solver->imax,
solver->jmaxLocal);
printf("RANK %d: imaxLocal : %d, jmaxLocal : %d\n", solver->rank,
solver->imax, solver->jmaxLocal);
solver->dx = params->xlength / params->imax;
solver->dy = params->ylength / params->jmax;
@ -133,8 +128,8 @@ void initSolver(Solver* solver, Parameter* params, int problem)
double dx = solver->dx;
double dy = solver->dy;
double* p = solver->p;
double* rhs = solver->rhs;
double *p = solver->p;
double *rhs = solver->rhs;
for (int j = 0; j < jmaxLocal + 2; j++) {
double y = solver->ys + j * dy;
@ -158,11 +153,10 @@ void initSolver(Solver* solver, Parameter* params, int problem)
}
}
void debug(Solver* solver)
{
void debug(Solver *solver) {
int imax = solver->imax;
int rank = solver->rank;
double* p = solver->p;
double *p = solver->p;
/* for( int j=0; j < solver->jmaxLocal+2; j++ ) { */
/* for( int i=0; i < solver->imax+2; i++ ) { */
@ -178,9 +172,11 @@ void debug(Solver* solver)
/* } */
/* if ( rank == 0 ) { */
/* printf("##########################################################\n"); */
/* printf("##########################################################\n");
*/
/* printf("## Exchange ghost layers\n"); */
/* printf("##########################################################\n"); */
/* printf("##########################################################\n");
*/
/* } */
/* exchange(solver); */
@ -192,8 +188,7 @@ void debug(Solver* solver)
}
}
int solve(Solver* solver)
{
int solve(Solver *solver) {
double r;
int it = 0;
double res, res1;
@ -210,8 +205,8 @@ int solve(Solver* solver)
double idx2 = 1.0 / dx2;
double idy2 = 1.0 / dy2;
double factor = omega * 0.5 * (dx2 * dy2) / (dx2 + dy2);
double* p = solver->p;
double* rhs = solver->rhs;
double *p = solver->p;
double *rhs = solver->rhs;
double epssq = eps * eps;
res = eps + 1.0;
@ -269,8 +264,7 @@ int solve(Solver* solver)
}
}
int solveRB(Solver* solver)
{
int solveRB(Solver *solver) {
double r;
int it = 0;
double res, res1;
@ -287,8 +281,8 @@ int solveRB(Solver* solver)
double idx2 = 1.0 / dx2;
double idy2 = 1.0 / dy2;
double factor = omega * 0.5 * (dx2 * dy2) / (dx2 + dy2);
double* p = solver->p;
double* rhs = solver->rhs;
double *p = solver->p;
double *rhs = solver->rhs;
int pass, jsw, isw;
double epssq = eps * eps;
@ -305,8 +299,8 @@ int solveRB(Solver* solver)
for (int j = 1; j < jmaxLocal + 1; j++) {
for (int i = isw; i < imax + 1; i += 2) {
double r = RHS(i, j) -
((P(i + 1, j) - 2.0 * P(i, j) + P(i - 1, j)) * idx2 +
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);
@ -345,8 +339,7 @@ int solveRB(Solver* solver)
}
}
int solveRBA(Solver* solver)
{
int solveRBA(Solver *solver) {
double r;
int it = 0;
double res;
@ -363,8 +356,8 @@ int solveRBA(Solver* solver)
double idx2 = 1.0 / dx2;
double idy2 = 1.0 / dy2;
double factor = omega * 0.5 * (dx2 * dy2) / (dx2 + dy2);
double* p = solver->p;
double* rhs = solver->rhs;
double *p = solver->p;
double *rhs = solver->rhs;
int pass, jsw, isw;
double rho = solver->rho;
double epssq = eps * eps;
@ -382,8 +375,8 @@ int solveRBA(Solver* solver)
for (int j = 1; j < jmaxLocal + 1; j++) {
for (int i = isw; i < imax + 1; i += 2) {
double r = RHS(i, j) -
((P(i + 1, j) - 2.0 * P(i, j) + P(i - 1, j)) * idx2 +
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) -= (omega * factor * r);
@ -417,13 +410,12 @@ int solveRBA(Solver* solver)
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 jmax = solver->jmax;
double* p = solver->p;
double *p = solver->p;
FILE* fp;
FILE *fp;
fp = fopen(filename, "w");
if (fp == NULL) {