MPI_Alloc_mem(3) man page (version 4.0.7)

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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)

USE MPI
! or the older form: INCLUDE ’mpif.h’
MPI_ALLOC_MEM(SIZE, INFO, BASEPTR, IERROR)
 INTEGER INFO, IERROR
 INTEGER(KIND=MPI_ADDRESS_KIND) SIZE, BASEPTR

Fortran 2008 Syntax

USE mpi_f08
MPI_Alloc_mem(size, info, baseptr, ierror)
 USE, INTRINSIC :: ISO_C_BINDING, ONLY
 INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) :: size
 TYPE(MPI_Info), INTENT(IN) :: info
 TYPE(C_PTR), INTENT(OUT) :: baseptr
 INTEGER, OPTIONAL, INTENT(OUT) :: ierror

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.

See Also

MPI_Free_mem

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Table of Contents

• Name
• Syntax
• C Syntax
• Fortran Syntax (see FORTRAN NOTES)
• Fortran 2008 Syntax
• Input Parameters
• Output Parameters
• Description
• Fortran Notes
• Errors
• See Also

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Page last modified: 16-Nov-2021
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