- . , (, /), , . α. T1. p : (1)
: S= (2)
, . : E= (3)
, α :
S= = (4)
, 10% , 10 .
2. /. MPI_Isend(), MPI_Irecv.
int MPI_Isend ( void* buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm comm, MPI_Request *request) -
buf (); count (); datatype (); dest - (); tag (); comm (); request ();
int MPI_Irecv ( void* buf, int count, MPI_Datatype datatype, int source, int tag, MPI_Comm comm, MPI_Request *request) -
IN buf (); IN count (); IN datatype (); IN source - (); IN tag (); IN comm (); OUT request ()
3:
#include "mpi.h"
#include <stdio.h>
main(int argc, char **argv) {
int numtasks, rank, next, prev, buf[2], tag1=1, tag2=2;
MPI_Request reqs[4];
MPI_Status stats[4];
MPI_Init(&argc,&argv);
MPI_Comm_size(MPI_COMM_WORLD, &numtasks);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
prev = rank - 1;
next = rank + 1;
if (rank == 0) prev = numtasks - 1;
if (rank == (numtasks - 1)) next = 0;
MPI_Irecv(&buf[0], 1, MPI_INT, prev, tag1, MPI_COMM_WORLD, &reqs[0]);
MPI_Irecv(&buf[1], 1, MPI_INT, next, tag2, MPI_COMM_WORLD, &reqs[1]);
MPI_Isend(&rank, 1, MPI_INT, prev, tag2, MPI_COMM_WORLD, &reqs[2]);
MPI_Isend(&rank, 1, MPI_INT, next, tag1, MPI_COMM_WORLD, &reqs[3]);
MPI_Waitall(4, reqs, stats);
printf("me %d recv %d %d\n",rank,buf[0],buf[1]);
MPI_Finalize();
}