17.2.456. MPI_Win_shared_query

MPI_Win_shared_query - Query a shared memory window

17.2.456.1. SYNTAX

17.2.456.1.1. C Syntax

#include <mpi.h>

int MPI_Win_shared_query (MPI_Win win, int rank, MPI_Aint *size,
                          int *disp_unit, void *baseptr)

17.2.456.1.2. Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_WIN_SHARED_QUERY(WIN, RANK, SIZE, DISP_UNIT, BASEPTR, IERROR)
        INTEGER WIN, RANK, DISP_UNIT, IERROR
        INTEGER(KIND=MPI_ADDRESS_KIND) SIZE, BASEPTR

17.2.456.1.3. Fortran 2008 Syntax

USE mpi_f08
MPI_Win_shared_query(win, rank, size, disp_unit, baseptr, ierror)
     USE, INTRINSIC :: ISO_C_BINDING, ONLY : C_PTR
     TYPE(MPI_Win), INTENT(IN) :: win
     INTEGER, INTENT(IN) :: rank
     INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(OUT) :: size
     INTEGER, INTENT(OUT) :: disp_unit
     TYPE(C_PTR), INTENT(OUT) :: baseptr
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror

17.2.456.2. INPUT PARAMETERS

  • win: Shared memory window object (handle).

  • rank: Rank in the group of window win (non-negative integer) or MPI_PROC_NULL.

17.2.456.3. OUTPUT PARAMETERS

  • size: Size of the window segment (non-negative integer).

  • disp_unit: Local unit size for displacements, in bytes (positive integer).

  • baseptr: Address for load/store access to window segment (choice).

  • IERROR: Fortran only: Error status (integer).

17.2.456.4. DESCRIPTION

MPI_Win_shared_query queries the process-local address for remote memory segments created with MPI_Win_allocate_shared. This function can return different process-local addresses for the same physical memory on different processes. The returned memory can be used for load/store accesses subject to the constraints defined in MPI-3.1 section 11.7. This function can only be called with windows of flavor MPI_WIN_FLAVOR_SHARED. If the passed window is not of flavor MPI_WIN_FLAVOR_SHARED, the error MPI_ERR_RMA_FLAVOR is raised. When rank is MPI_PROC_NULL, the pointer, disp_unit, and size returned are the pointer, disp_unit, and size of the memory segment belonging the lowest rank that specified size > 0. If all processes in the group attached to the window specified size = 0, then the call returns size = 0 and a baseptr as if MPI_Alloc_mem was called with size = 0.

17.2.456.5. C NOTES

The parameter baseptr is of type void * to allow passing any pointer object for this parameter. The provided argument should be a pointer to a pointer of arbitrary type (e.g. void **).

17.2.456.6. ERRORS

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.

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.