typeub.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 <math.h>
#include <stdio.h>
#include "mpi.h"

#if defined(NEEDS_STDLIB_PROTOTYPES)
#include "protofix.h"
#endif

/*
 *	Trying to manipulate the extent of a datatype with succesive
 *	calls to MPI_Type_struct.  Tests that a MPI_UB buried within
 *      a structure is found.  From [e-mail] (modified to
 *      fit test structure).
 */
int main( int argc, char **argv )
{
   int          errs = 0, toterrs, rank; 
   MPI_Aint   	extent;
   int		blens[2];
   MPI_Aint	displ[2];
   MPI_Datatype types[2];
   MPI_Datatype type1,type2,type3;
   MPI_Aint     extent1, extent2, extent3;

   MPI_Init( &argc, &argv );

  /*	2 blocks of 1 int each, stride of 4 ; expect extent to be 20
   */
   MPI_Type_vector( 2, 1, 4, MPI_INT, &type1 );
   MPI_Type_commit( &type1 );
   MPI_Type_extent( type1, &extent );
   extent1 = 5 * sizeof(int);
   if (extent != extent1) {
       errs++;
       printf("extent(type1)=%ld\n",(long)extent);
       }

   blens[0]=1;
   blens[1]=1;
   displ[0]=0;
   displ[1]=sizeof(int)*4;
   types[0]=type1;
   types[1]=MPI_UB;
   extent2 = displ[1];

  /*	using MPI_UB and Type_struct, monkey with the extent, making it 16
   */
   MPI_Type_struct( 2, blens, displ, types, &type2 );
   MPI_Type_commit( &type2 );
   MPI_Type_extent( type2, &extent );
   if (extent != extent2) {
       errs++;
       printf("extent(type2)=%ld\n",(long)extent);
       }

  /*	monkey with the extent again, making it 4
   *  	===> MPICH gives 4	
   *  	===> MPIF gives 16, the old extent	
   */
   displ[1]=sizeof(int);
   types[0]=type2;
   types[1]=MPI_UB;
   extent3 = extent2;

   MPI_Type_struct( 2, blens, displ, types, &type3 );
   MPI_Type_commit( &type3 );

   MPI_Type_extent( type3, &extent );
   if (extent != extent3) {
       errs++;
       printf("extent(type3)=%ld\n",(long)extent);
       }

   MPI_Type_free( &type1 );
   MPI_Type_free( &type2 );
   MPI_Type_free( &type3 );

   MPI_Allreduce( &errs, &toterrs, 1, MPI_INT, MPI_SUM, MPI_COMM_WORLD );
   MPI_Comm_rank( MPI_COMM_WORLD, &rank );
   if (rank == 0) {
       if (toterrs == 0) printf( "No errors\n" );
       else              printf( "Found %d errors\n", toterrs );
   }


   MPI_Finalize();
   return 0;
}