/**
* <Parallel programming technology for high performance computing>
*
* @Copyright Du Zhihui :edited
* Li Sanli :review
* Chen Yu Liu Peng :proofreading
*
* Rong Tao study note: 2017.10
*
*/
/**
* mpicc -o outfile Demo.c
* mpirun -n 2 ./outfile > out.txt
*
*/
#include "mpi.h"
#include <stdio.h>
#include <math.h>
int main(int argc,char *argv[])
{
int myid, numprocs;
char message[20];
MPI_Status status;
MPI_Init(&argc,&argv);
MPI_Comm_rank(MPI_COMM_WORLD,&myid);
MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
if(myid == 0)
{
strcpy(message, "hello, process I");
MPI_Send(message, 20, MPI_CHAR, 1, 999, MPI_COMM_WORLD);
}
else if(myid == 1)
{
MPI_Recv(message, 20, MPI_CHAR, 0, 999, MPI_COMM_WORLD, &status);
printf("received : %s\n",message);
}
MPI_Finalize();
}
/**
MPI_INTEGER
MPI_REAL
MPI_DOUBLE_PRECISION
MPI_COMPLEX
MPI_LOGICAL
MPI_CHARACTER
MPI_BYTE
MPI_PACKED
*/
编译与运行:
-bash-4.1$ mpicc -o a Demo_02_MPI_Send_MPI_Recv_01.c
-bash-4.1$ mpirun -n 2 ./a
received : hello, process I
-bash-4.1$
再一个例子:
这个例子展示了所有节点互相通信,直至到rank号最大的节点终止
#include "mpi.h"
#include <stdio.h>
#include <math.h>
int main(int argc,char *argv[])
{
int myid, numprocs;
int value;
MPI_Status status;
MPI_Init(&argc,&argv);
MPI_Comm_rank(MPI_COMM_WORLD,&myid);
MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
do{
if(myid == 0)
{
scanf("%d",&value);
if(numprocs > 1)
{
MPI_Send(&value, 1, MPI_INT, myid+1, 0, MPI_COMM_WORLD);
fprintf(stderr,"%d send (%d) to %d\n",myid, value, myid+1);
}
}
else
{
MPI_Recv(&value, 1, MPI_INT, myid-1, 0, MPI_COMM_WORLD, &status);
fprintf(stderr,"%d receive (%d) to %d\n",myid, value, myid+1);
if(myid < numprocs-1)
{
MPI_Send(&value, 1, MPI_INT, myid+1, 0, MPI_COMM_WORLD);
fprintf(stderr,"%d send (%d) to %d\n",myid, value, myid+1);
}
}
MPI_Barrier(MPI_COMM_WORLD);
}while(value >= 0);
MPI_Barrier(MPI_COMM_WORLD);
MPI_Finalize();
}
编译与运行:
-bash-4.1$ mpicc -o a Demo_02_MPI_Send_MPI_Recv_02.c
-bash-4.1$ mpirun -n 3 ./a
1
0 send (1) to 1
1 receive (1) to 2
1 send (1) to 2
2 receive (1) to 3
2
0 send (2) to 1
1 receive (2) to 2
1 send (2) to 2
2 receive (2) to 3
-1
0 send (-1) to 1
1 receive (-1) to 2
1 send (-1) to 2
2 receive (-1) to 3
-bash-4.1$
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MPI_Send和MPI_Recv(初识1)
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