MPI_Alloc_mem(3)

NAME
     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 set the baseptr argument to NULL and return
         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)