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Hi, I'm Mariano Guerra, below is my blog, if you want to learn more about me and what I do check a summary here: marianoguerra.github.io or find me on twitter @warianoguerra or Mastodon @marianoguerra@hachyderm.io

correcciones de problemas de MPI

alguien me paso el tip de que el broadcast de MPI es una operacion colectiva y que no tiene que ir en el rank 0 si no que todos lo tienen que ejecutar ya que tiene el receive implicito, asi que aca los 2 programas corregidos (los que no imprimian los valores de los procesos que no fueran el master).

plus un arreglo en la declaracion de la estructura en el segundo programa.

#include <stdio.h>
#include <mpi.h>

int main (int argc, char** argv) {
int rank, size, value, i;
MPI_Status status;

MPI_Init (&argc, &argv); /* starts MPI */
MPI_Comm_rank (MPI_COMM_WORLD, &rank); /* get current process id */
MPI_Comm_size (MPI_COMM_WORLD, &size); /* get number of processes */

do {
if(rank == 0) {
printf("give me a value: ");
scanf("%d", &value);
}

MPI_Bcast(&value, 1, MPI_INT, 0, MPI_COMM_WORLD);
printf("process %d received %d\n", rank, value);
fflush(stdout);
} while(value >= 0);
printf("negative value, closing\n");

MPI_Finalize();
return 0;
}

#include <stdio.h>
#include <mpi.h>

MPI_Datatype IntDoubleType = 0;

typedef struct {
int value_int;
double value_double;
}IntDouble;

MPI_Datatype create_int_double_type() {
if(IntDoubleType == 0) {
MPI_Aint array_of_displacements[2];
MPI_Datatype array_of_types[2];
int array_of_blocklengths[2];

array_of_displacements[0] = 0;
array_of_types[0] = MPI_INT;
array_of_blocklengths[0] = sizeof(int);

array_of_displacements[1] = sizeof(int);
array_of_types[1] = MPI_DOUBLE;
array_of_blocklengths[1] = sizeof(double);

MPI_Type_struct(1, array_of_blocklengths, array_of_displacements,
array_of_types, &IntDoubleType);
MPI_Type_commit(&IntDoubleType);

}

return IntDoubleType;
}

int main (int argc, char** argv) {
int rank, size, value_int, i;
double value_double;
IntDouble value;
MPI_Status status;

MPI_Init (&argc, &argv); /* starts MPI */
MPI_Comm_rank (MPI_COMM_WORLD, &rank); /* get current process id */
MPI_Comm_size (MPI_COMM_WORLD, &size); /* get number of processes */
create_int_double_type();

do {
if(rank == 0) {
printf("give me an int value: ");
scanf("%d", &value_int);
printf("give me a double value: ");
scanf("%lf", &value_double);
value.value_int = value_int;
value.value_double = value_double;
}

MPI_Bcast(&value, 1, IntDoubleType, 0, MPI_COMM_WORLD);
printf("process %d received %d %lf\n", rank, value.value_int,
value.value_double);
fflush(stdout);
} while(value.value_int >= 0);
printf("negative value, closing\n");

MPI_Finalize();
return 0;
}