NAME

       MPI_Win_shared_query  -   Query  the  size and base pointer for a patch of a shared memory
       window.

SYNOPSIS

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

       This function 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  3.0,  Section  11.7.  This  function  can  only  be  called  with windows of type
       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.

INPUT PARAMETERS

       win    - window object used for communication (handle)
       rank   - target rank

OUTPUT PARAMETERS

       size   - size of the segment at the given rank
       disp_unit
              - local unit size for displacements, in bytes (positive integer)
       baseptr
              -  base  pointer  in  the  calling  process'  address  space  of the shared segment
              belonging to the target rank.

THREAD AND INTERRUPT SAFETY

       This routine is thread-safe.  This means that this routine may be safely used by  multiple
       threads  without the need for any user-provided thread locks.  However, the routine is not
       interrupt safe.  Typically, this is due to the use of memory allocation routines  such  as
       malloc or other non-MPICH runtime routines that are themselves not interrupt-safe.

NOTES FOR FORTRAN

       All  MPI  routines  in  Fortran  (except  for MPI_WTIME and MPI_WTICK ) have an additional
       argument ierr at the end of the argument list.  ierr  is  an  integer  and  has  the  same
       meaning  as  the  return  value  of  the  routine  in  C.   In  Fortran,  MPI routines are
       subroutines, and are invoked with the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

ERRORS

       All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error value;  C  routines  as
       the  value of the function and Fortran routines in the last argument.  Before the value is
       returned, the current MPI error handler is called.  By default, this error handler  aborts
       the  MPI  job.   The  error  handler  may  be  changed  with  MPI_Comm_set_errhandler (for
       communicators), MPI_File_set_errhandler (for files), and MPI_Win_set_errhandler  (for  RMA
       windows).   The  MPI-1  routine  MPI_Errhandler_set may be used but its use is deprecated.
       The predefined error handler MPI_ERRORS_RETURN may be used to cause  error  values  to  be
       returned.   Note  that  MPI  does  not  guarentee that an MPI program can continue past an
       error; however, MPI implementations will attempt to continue whenever possible.

       MPI_SUCCESS
              - No error; MPI routine completed successfully.
       MPI_ERR_ARG
              - Invalid argument.  Some argument is invalid and is not identified by  a  specific
              error class (e.g., MPI_ERR_RANK ).
       MPI_ERR_RANK
              -  Invalid  source or destination rank.  Ranks must be between zero and the size of
              the  communicator  minus  one;  ranks  in  a  receive  (  MPI_Recv  ,  MPI_Irecv  ,
              MPI_Sendrecv , etc.) may also be MPI_ANY_SOURCE .

       MPI_ERR_WIN
              - Invalid MPI window object

SEE ALSO

       MPI_Win_allocate_shared

LOCATION

       src/mpi/rma/win_shared_query.c

                                            4/24/2013                     MPI_Win_shared_query(3)