NAME

       MPI_Win_lock_all -  Begin an RMA access epoch at all processes on the given window.

SYNOPSIS

       int MPI_Win_lock_all(int assert, MPI_Win win)

       Starts  an RMA access epoch to all processes in win, with a lock type of MPI_Lock_shared .
       During the epoch, the calling process can access the window memory on all processes in win
       by  using  RMA  operations.  A  window  locked with MPI_Win_lock_all must be unlocked with
       MPI_Win_unlock_all .  This routine is not collective -- the ALL refers to a  lock  on  all
       members of the group of the window.

INPUT PARAMETERS

       assert - Used to optimize this call; zero may be used as a default.  See notes. (integer)
       win    - window object (handle)

NOTES

       This call is not collective.

       The  assert  argument  is  used  to  indicate  special  conditions  for  the fence that an
       implementation may use to optimize the MPI_Win_lock_all  operation.   The  value  zero  is
       always  correct.  Other assertion values may be or'ed together.  Assertions that are valid
       for MPI_Win_lock_all are:

       MPI_MODE_NOCHECK

              - No other process holds, or will attempt to acquire a conflicting lock, while  the
              caller  holds  the window lock. This is useful when mutual exclusion is achieved by
              other means, but the coherence operations that may be  attached  to  the  lock  and
              unlock calls are still required.

              There   may   be  additional  overheads  associated  with  using  MPI_Win_lock  and
              MPI_Win_lock_all concurrently on the same window. These overheads could be  avoided
              by specifying the assertion MPI_MODE_NOCHECK when possible

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_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
       MPI_ERR_OTHER
              - Other error; use MPI_Error_string to get more information about this error code.

SEE ALSO

       MPI_Win_unlock_all

LOCATION

       src/mpi/rma/win_lock_all.c

                                            4/24/2013                         MPI_Win_lock_all(3)