Programming Based on Message Passing
As we know, the programming model based on message passing uses high level programming languages like C/C++ along with a number of message passing libraries like PVM and MPI. Here, given an example program of message passing.
Example 1: Addition of array elements using two processors.
In this problem, we have to search the sum of all the elements of an array A of size n. We shall separate n elements into two groups of roughly equal size. The first [n/2] elements are added by the first processor, P0, and last [n/2] elements the by second processor, P1. The two sums then are added to get the final result. The program is given below:
Program for P0
#include
#define n 100
int main(int argc, char **argv) {
int A[n];
int sum0 =0, sum1=0,sum; MPI_Init(&argc, &argv);
for( int i=0;i
scanf("%d", &A[i]);
MPI_Send( &n/2, n/2, MPI_INT,1, 0, MPI_COMM_WORLD);
for(i=1; i
sum0+=A[i];
sum1=MPI_Recv(&n/2, n/2, MPI_INT,1, 0, MPI_COMM_WORLD);
sum=sum0+sum1; printf("%d",sum); MPI_Finalize();
}
Program for P1,
int func( int B[int n])
{
MPI_Recv(&n/2, n/2, MPI_INT,0, 0, MPI_COMM_WORLD);
int sum1=0 ;
for (i=0; i
sum1+=B[i];
MPI_Send( 0, n/2, MPI_INT,0, 0, MPI_COMM_WORLD);
}