MPI_Alloc_mem - Allocates special memory
SYNOPSIS
C:
#include <mpi.h>
int MPI_Alloc_mem( size, info, *baseptr)
MPI_Aint *size;
MPI_Info *info;
void* *baseptr;
Fortran:
INCLUDE "mpif.h" (or USE MPI)
INTEGER info, ierror
INTEGER(KIND=MPI_ADDRESS_KIND) size, baseptr
CALL MPI_ALLOC_MEM(size, info, baseptr, ierror)
DESCRIPTION
The MPI_Alloc_mem function allocates special memory. It is
used in conjunction with MPI_Free_mem. Like any other
dynamically allocated memory, a call to MPI_Alloc_mem
should be paired by a later call to MPI_Free_mem. If no
memory is available, baseptr is set to NULL, and
MPI_ERR_NO_MEM is returned.
This routine accepts the following parameters:
size Specifies the size of the desired chunk of
memory.
info Specifies an object that can be used to provide
directives that control the desired location of
the allocated memory.
baseptr Specifies the initial address of the memory
segment that has been allocated.
ierror Specifies the return code value for successful
completion. A return value of MPI_ERR_NO_MEM
indicates failure.
NOTES
The MPI_Alloc_mem function has the following limitations:
* In C, the routine works with -n32 and -64 applications
on IRIX. For -n32, however, if you have not
explicitly linked in -lsma, the routine will always
MPI_ERR_NO_MEM. On Linux, only 64-bit C applications
are supported.
* In Fortran, the routine works only with 64-bit
applications. Attempting to link a Fortran -n32
application might generate an error at link time.
* On IRIX, to use this function for memory allocation,
the user must set the SMA_GLOBAL_ALLOC shell variable.
You can adjust the total available memory that
MPI_Alloc_mem can allocate by using the
SMA_GLOBAL_HEAP_SIZE shell variable. The default when
SMA_GLOBAL_ALLOC is set is 32 Mbytes per process for
64-bit MPI applications. Note that setting the
MPI_NO_LIBSMA shell variable always results in a
return value of MPI_ERR_NO_MEM. For additional
information on setting this and related shell
variables, see the MPI(1) man page.
* On Linux, MPI_Alloc_mem allocates memory from the
private heap. No additional environment variable
settings are necessary.
* Currently, the info object is not used, but the data
structure for managing memory allocation keeps a copy
of this info structure, to be used later on.
EXAMPLE
The following example shows how MPI_Alloc_mem and
MPI_Free_mem may be used from Fortran.
DOUBLE PRECISION U
POINTER (P,U(0:50,0:20))
INTEGER(KIND=MPI_ADDRESS_KIND) SIZE
INTEGER SIZEOFDOUBLE,IERROR
! CAREFUL WITH SIZE (MUST BE MPI_ADDRESS_KIND)
SIZE = 51 * 21 * 8
CALL MPI_ALLOC_MEM(SIZE,MPI_INFO_NULL,P,IERROR)
CALL MPI_FREE_MEM(U,IERROR) ! NOT P!
SEE ALSO
MPI_Free_mem(1)
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