MPI_Alloc

MPI_Alloc_mem

Section: Open MPI (3) Updated: Oct 05, 2010 Local index Up

NAME

MPI_Alloc_mem - Allocates a specified memory segment.

SYNTAX

C Syntax

#include <mpi.h>
int MPI_Alloc_mem(MPI_Aint size, MPI_Info info, void *baseptr)

Fortran Syntax (see FORTRAN NOTES)

INCLUDE 'mpif.h'
MPI_ALLOC_MEM(SIZE, INFO, BASEPTR, IERROR) 
        INTEGER INFO, IERROR 
        INTEGER(KIND=MPI_ADDRESS_KIND) SIZE, BASEPTR

C++ Syntax

#include <mpi.h>
void* MPI::Alloc_mem(MPI::Aint size, const MPI::Info& info)

INPUT PARAMETERS

size: Size of memory segment in bytes (nonnegative integer).
info: Info argument (handle).

OUTPUT PARAMETERS

baseptr: Pointer to beginning of memory segment allocated.
IERROR: Fortran only: Error status (integer).

DESCRIPTION

MPI_Alloc_mem allocates size bytes of memory. The starting address of this memory is returned in the variable base.

FORTRAN NOTES

There is no portable FORTRAN 77 syntax for using MPI_Alloc_mem. There is no portable Fortran syntax for using pointers returned from MPI_Alloc_mem. However, MPI_Alloc_mem can be used with Sun Fortran compilers.

From FORTRAN 77, you can use the following non-standard declarations for the SIZE and BASEPTR arguments:

           INCLUDE "mpif.h"
           INTEGER*MPI_ADDRESS_KIND SIZE, BASEPTR

From either FORTRAN 77 or Fortran 90, you can use "Cray pointers" for the BASEPTR argument. Cray pointers are described further in the Fortran User's Guide and are supported by many Fortran compilers. For example,

           INCLUDE "mpif.h"
           REAL*4 A(100,100)
           POINTER (BASEPTR, A)
           INTEGER*MPI_ADDRESS_KIND SIZE

           SIZE = 4 * 100 * 100
           CALL MPI_ALLOC_MEM(SIZE,MPI_INFO_NULL,BASEPTR,IERR)

           ! use A

           CALL MPI_FREE_MEM(A, IERR)

ERRORS

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI:Exception object.

Before the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

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Time: 21:50:34 GMT, April 16, 2011