Files
Presentations/EVI - 2016/EVI - 12/Examples/hello_mpi_no_status.c

63 lines
2.0 KiB
C
Executable File

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <mpi.h>
#define BUFSIZE 128 /* Enough space for our needs. */
#define TAG 0 /* Message tag. */
int main(int argc, char *argv[]) {
char buff[BUFSIZE];
int rank;
/* Start with MPI_Init and get the rank. */
MPI_Init(&argc,&argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
/***********************************************************************
* MASTER PROCESS *
***********************************************************************/
if(rank == 0) {
int size, i;
/* Get the number of processes. */
MPI_Comm_size(MPI_COMM_WORLD, &size);
printf("MASTER: %d processes available.\n", size);
/* Send data to the slaves. */
for(i = 1; i < size; i++) {
memset(buff, 0, BUFSIZE);
sprintf(buff, "Hello, Process %d! ", i);
MPI_Send(buff, BUFSIZE, MPI_CHAR, i, TAG, MPI_COMM_WORLD);
}
/* Receive answers from the slaves. */
for(i = 1; i < size; i++) {
memset(buff, 0, BUFSIZE);
MPI_Recv(buff, BUFSIZE, MPI_CHAR, i, TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
printf("MASTER: Received \"%s\"\n", buff);
}
/***********************************************************************
* SLAVE PROCESS *
***********************************************************************/
} else {
/* Receive orders from the master. */
memset(buff, 0, BUFSIZE);
MPI_Recv(buff, BUFSIZE, MPI_CHAR, 0 /*Master's rank*/, TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
printf("SLAVE %d: Master says: \"%s\"\n", rank, buff);
/* Calculate something. */
memset(buff, 0, BUFSIZE);
sprintf(buff, "Processor %d reporting for duty!", rank);
/* Send answer to the master. */
MPI_Send(buff, BUFSIZE, MPI_CHAR, 0, TAG, MPI_COMM_WORLD);
}
/* End with MPI_Finalize. */
MPI_Finalize();
return EXIT_SUCCESS;
}