life_g.c

MPICH是MPI的重要研究,提供了一系列的接口函数,为并行计算的实现提供了编程环境.

#include <mpi.h>
#define MPE_GRAPHICS
#include "mpe.h"
#include <stdio.h>

static MPE_XGraph graph;

static char *displayname = 0;
extern void   srand48();
extern double drand48();
extern char * malloc();
static int width = 400, height = 400;

#define BORN 1
#define DIES 0

/* The Life function */
double life(matrix_size, ntimes, comm)
int matrix_size;
int ntimes;
MPI_Comm comm;
{
  int      rank, size ;
  int      next, prev ;
  int      i, j, k;
  int      mysize, sum ;
  int    **matrix, **temp, **addr ;
  double   slavetime, totaltime, starttime ;
  int      my_offset;

  /* Determine size and my rank in communicator */
  MPI_Comm_size(comm, &size) ;
  MPI_Comm_rank(comm, &rank) ;

  /* Set neighbors */
  if (rank == 0) 
    prev = MPI_PROC_NULL;
  else
    prev = rank-1;
  if (rank == size - 1)
    next = MPI_PROC_NULL;
  else
    next = rank+1;

  /* Determine my part of the matrix */
  mysize = matrix_size/size + ((rank < (matrix_size % size)) ? 1 : 0 ) ;
  my_offset = rank * (matrix_size/size);
  if (rank > (matrix_size % size)) my_offset += (matrix_size % size);
  else                             my_offset += rank;

  /* allocate the memory dynamically for the matrix */
  matrix = (int **)malloc(sizeof(int *)*(mysize+2)) ;
  temp = (int **)malloc(sizeof(int *)*(mysize+2)) ;
  for (i = 0; i < mysize+2; i++) {
    matrix[i] = (int *)malloc(sizeof(int)*(matrix_size+2)) ;
    temp[i] = (int *)malloc(sizeof(int)*(matrix_size+2)) ;
  }

  /* Initialize the boundaries of the life matrix */
  for (j = 0; j < matrix_size+2; j++)
    matrix[0][j] = matrix[mysize+1][j] = temp[0][j] = temp[mysize+1][j] = DIES ;
  for (i = 0; i < mysize+2; i++)
    matrix[i][0] = matrix[i][matrix_size+1] = temp[i][0] = temp[i][matrix_size+1] = DIES ;

  /* Initialize the life matrix */
  for (i = 1; i <= mysize; i++)  {
    srand48((long)(1000^(i-1+mysize))) ;
    for (j = 1; j<= matrix_size; j++)
      if (drand48() > 0.5)  
        matrix[i][j] = BORN ;
      else
        matrix[i][j] = DIES ;
  }


  /* Open the graphics display */
  MPE_Open_graphics( &graph, MPI_COMM_WORLD, displayname, 
		   -1, -1, width, height, 0 );

  /* Play the game of life for given number of iterations */
  starttime = MPI_Wtime() ;
  for (k = 0; k < ntimes; k++) {
    MPI_Request      req[4];
    MPI_Status       status[4];

    /* Send and receive boundary information */
    MPI_Isend(&matrix[1][0],matrix_size+2,MPI_INT,prev,0,comm,req); 
    MPI_Irecv(&matrix[0][0],matrix_size+2,MPI_INT,prev,0,comm,req+1);
    MPI_Isend(&matrix[mysize][0],matrix_size+2,MPI_INT,next,0,comm,req+2);
    MPI_Irecv(&matrix[mysize+1][0],matrix_size+2,MPI_INT,next,0,comm,req+3);
    MPI_Waitall(4, req, status);

    /* For each element of the matrix ... */ 
    for (i = 1; i <= mysize; i++) {
      for (j = 1; j < matrix_size+1; j++) {

        /* find out the value of the current cell */
        sum = matrix[i-1][j-1] + matrix[i-1][j] + matrix[i-1][j+1] 
          + matrix[i][j-1] + matrix[i][j+1] 
            + matrix[i+1][j-1] + matrix[i+1][j] + matrix[i+1][j+1] ;
        
        /* check if the cell dies or life is born */
        if (sum < 2 || sum > 3)
          temp[i][j] = DIES ;
        else if (sum == 3)
          temp[i][j] = BORN ;
        else
          temp[i][j] = matrix[i][j] ;
	{ int xloc, yloc, xwid, ywid;
	  xloc = ((my_offset + i - 1) * width) / matrix_size;
	  yloc = ((j - 1) * height) / matrix_size;
	  xwid = ((my_offset + i) * width) / matrix_size - xloc;
	  ywid = (j * height) / matrix_size - yloc;
	  MPE_Fill_rectangle( graph, xloc, yloc, xwid, ywid, temp[i][j] );
	  }
      }
    }
    MPE_Update( graph );
    /* Swap the matrices */
    addr = matrix ;
    matrix = temp ;
    temp = addr ;
  }

  /* Return the average time taken/processor */
  slavetime = MPI_Wtime() - starttime;
  MPI_Reduce (&slavetime, &totaltime, 1, MPI_DOUBLE, MPI_SUM, 0, comm);
  return (totaltime/(double)size);}
  

int main(argc, argv)
int argc ;
char *argv[] ;
{
  int rank, N, iters ;
  double time ;
  
  MPI_Init (&argc, &argv);
  MPI_Comm_rank(MPI_COMM_WORLD, &rank) ;

  /* If I'm process 0, determine the matrix size and # of iterations */
  /* This relies on the MPI implementation properly flushing output
     that does not end in a newline.  MPI does not require this, though
     high-quality implementations will do this.
   */
#if !defined (SGI_MPI) && !defined (IBM_MPI)
  if ( rank == 0 ) {
    printf("Matrix Size : ") ;
    scanf("%d",&N) ;
    printf("Iterations : ") ;
    scanf("%d",&iters) ;
  }
#else
  N=20;
  iters=50;
#endif
  
  /* Broadcast the size and # of iterations to all processes */
  MPI_Bcast(&N, 1, MPI_INT, 0, MPI_COMM_WORLD) ;
  MPI_Bcast(&iters, 1, MPI_INT, 0, MPI_COMM_WORLD) ;

  if (argc > 2 && strcmp( argv[1], "-display" ) == 0) {
      displayname = malloc( strlen( argv[2] ) + 1 );
      strcpy( displayname, argv[2] );
      }
  /* Call the life routine */
  time = life ( N, iters, MPI_COMM_WORLD );

  /* Print the total time taken */
  if (rank == 0)
    printf("[%d] Life finished in %lf seconds\n",rank,time/100);

  MPE_Close_graphics(&graph);
  MPI_Finalize();
}