sudo apt-get install libcr-dev mpich2 mpich2-doc

/* C Example */
#include <mpi.h>
#include <stdio.h>

int main (int argc, char* argv[])
{
 int rank, size;

 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 */
 printf( "Hello world from process %d of %d\n", rank, size );
 MPI_Finalize();
 return 0;
}

mpicc mpi_hello.c -o hello
mpirun -np 2 ./hello
Hello world from process 0 of 2
Hello world from process 1 of 2

mpirun --version

mpirun (Open MPI) 1.6.5
Report bugs to http://www.open-mpi.org/community/help/

#include <mpi.h>
#include <stdio.h>
#define MATRIX_SIZE 10
#define FROM_MASTER 1 //这里的类型可以区分消息的种类，以便区分worker发送来的结果
#define FROM_CHILD 2 
#define MASTER 0
MPI_Status status;
int myid,numprocess;
//最终保存的结果
int ans [MATRIX_SIZE*MATRIX_SIZE];
int A[MATRIX_SIZE*MATRIX_SIZE],B[MATRIX_SIZE*MATRIX_SIZE];
//读取文件，注意读取文件要放在master里，不然会读两遍，出现错误
void readFile(){
  FILE* fina,*finb;
  fina=fopen("a.txt","r");
  int i;
  for (i = 0; i < MATRIX_SIZE*MATRIX_SIZE ; ++i)
  {
    fscanf(fina,"%d ",&A[i]);
  }
  fclose(fina);
  finb=fopen("b.txt","r");
  for(i=0;i<MATRIX_SIZE*MATRIX_SIZE;i++)
    fscanf(finb,"%d ",&B[i]);
  fclose(finb);
  printf("read file ok\n");
}
int master(){
  int workid,dest,i,j;
  printf("numprocess %d\n",numprocess );
  //给每个worker发送B矩阵过去
  for(i=0;i<numprocess-1;i++){
    //send B matrix
    MPI_Send(&B,MATRIX_SIZE*MATRIX_SIZE,MPI_INT,i+1,FROM_MASTER,MPI_COMM_WORLD);
  }
  //开始给每个worker分配任务，取模即可
  for (i = 0; i < MATRIX_SIZE; i++)
  {
    //attention: num of workers is numprocess-1
    workid=i%(numprocess-1)+1;
    //send single line in A
    MPI_Send(&A[i*MATRIX_SIZE],MATRIX_SIZE,MPI_INT,workid,FROM_MASTER,MPI_COMM_WORLD);
  }

  //等待从worker发送来的数据
  int tempLine[MATRIX_SIZE];
  for (i = 0; i < MATRIX_SIZE*MATRIX_SIZE; i++)
  {
    ans[i]=0;
  }
  for (i = 0; i < MATRIX_SIZE; ++i)
  {
    int myprocess=i%(numprocess-1)+1;
    printf("Master is waiting %d\n",myprocess);
    //receive every line from every process
    MPI_Recv(&tempLine,MATRIX_SIZE,MPI_INT,myprocess,FROM_CHILD,MPI_COMM_WORLD,&status);
    //发送过来的都是计算好了的一行的数据，直接组装到ans里就行
    for(j=0;j<MATRIX_SIZE;j++){
      ans[MATRIX_SIZE*i+j]=tempLine[j];
    }
    printf("Master gets %d\n",i);
  }

  for(i=0;i<MATRIX_SIZE*MATRIX_SIZE;i++){
    printf("%d ",ans[i] );
    if(i%MATRIX_SIZE==(MATRIX_SIZE-1))printf("\n");
  }
  printf("The Master is out\n");

}
int worker(){
  int mA[MATRIX_SIZE],mB[MATRIX_SIZE*MATRIX_SIZE],mC[MATRIX_SIZE];
  int i,j,bi;
  MPI_Recv(&mB,MATRIX_SIZE*MATRIX_SIZE,MPI_INT,MASTER,FROM_MASTER,MPI_COMM_WORLD,&status);
  //接收来自master的A的行
  for(i=0;i<MATRIX_SIZE/(numprocess-1);i++){
    MPI_Recv(&mA,MATRIX_SIZE,MPI_INT,MASTER,FROM_MASTER,MPI_COMM_WORLD,&status);
    //矩阵乘法，A 的一行和B矩阵相乘
    for(bi=0;bi<MATRIX_SIZE;bi++){
      mC[bi]=0;
      for(j=0;j<MATRIX_SIZE;j++){
        mC[bi]+=mA[j]*mB[bi*MATRIX_SIZE+j];
      }
    }
    MPI_Send(&mC,MATRIX_SIZE,MPI_INT,MASTER,FROM_CHILD,MPI_COMM_WORLD);
  }
  //如果处于余数范围内，则需要多计算一行
  if(MATRIX_SIZE%(numprocess-1)!=0){
    if (myid<=(MATRIX_SIZE%(numprocess-1)))
    {
      MPI_Recv(&mA,MATRIX_SIZE,MPI_INT,MASTER,FROM_MASTER,MPI_COMM_WORLD,&status);
      for(bi=0;bi<MATRIX_SIZE;bi++){
        mC[bi]=0;
        for(j=0;j<MATRIX_SIZE;j++){
          mC[bi]+=mA[j]*mB[bi*MATRIX_SIZE+j];
        }
      }
      MPI_Send(&mC,MATRIX_SIZE,MPI_INT,MASTER,FROM_CHILD,MPI_COMM_WORLD);
    }
  }
  printf("The worker %d is out\n",myid);
}
int main(int argc, char **argv)
{
  MPI_Init (&argc, &argv); 
  MPI_Comm_rank(MPI_COMM_WORLD,&myid);
  MPI_Comm_size(MPI_COMM_WORLD,&numprocess);

  if(myid==MASTER){
    readFile();
    master();
  }
  if(myid>MASTER){
    worker();
  }

  MPI_Finalize();
  return 0;
}

int MPI_Init( int *argc, char * * * argv )

int MPI_Finalize(void)

int MPI_Comm_rank(MPI_Comm comm, int *rank)

int MPI_Comm_size(MPI_Comm comm, int *size)

int MPI_Send(void *buf, int count, MPI_Datatype dataytpe, int dest, int tag, MPI_Comm comm)

 int MPI_Recv(void *buf, int count, MPI_Datatype datatyepe,int source, int tag, MPI_Comm comm, MPI_Status *status)

mpicc -o programname programname.c

 mpirun –np N programname