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mpi_hello0.c
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51 lines (44 loc) · 1.37 KB
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/* File: mpi_hello.c
*
* Purpose: A "hello,world" program that uses MPI
*
* Compile: mpicc -g -Wall -o mpi_hello mpi_hello.c
* Run: mpiexec -n<number of processes> mpi_hello
*
* Input: None
* Output: A greeting from each process
*
* Algorithm: Each process sends a message to process 0,
* which prints the messages it has received,
* as well as its own message.
*/
#include <stdio.h>
#include <string.h> /* For strlen */
#include <mpi.h> /* For MPI functions, etc */
const int MAX_STRING = 100;
int main(void) {
char greeting[MAX_STRING];
int my_rank, p, q;
/* Start up MPI */
MPI_Init(NULL, NULL);
/* Get the number of processes */
MPI_Comm_size(MPI_COMM_WORLD, &p);
/* Get my rank among all the processes */
MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
if (my_rank == 0) {
printf("Greetings from process %d of %d\n", my_rank, p);
for (q = 1; q < p; q++) {
MPI_Recv(greeting, MAX_STRING, MPI_CHAR, q,
0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
printf("%s\n", greeting);
}
} else {
sprintf(greeting, "Greetings from process %d of %d",
my_rank, p);
MPI_Send(greeting, strlen(greeting)+1, MPI_CHAR, 0, 0,
MPI_COMM_WORLD);
}
/* Shut down MPI */
MPI_Finalize();
return 0;
} /* main */