NAME¶
MPI_Win_lock - Begin an RMA access epoch at the target process.
SYNOPSIS¶
int MPI_Win_lock(int lock_type, int rank, int assert, MPI_Win win)
- lock_type
- - Indicates whether other processes may access the target window at the
same time (if MPI_LOCK_SHARED ) or not ( MPI_LOCK_EXCLUSIVE
)
- rank
- - rank of locked window (nonnegative integer)
- assert
- - Used to optimize this call; zero may be used as a default. See notes.
(integer)
- win
- - window object (handle)
NOTES¶
The name of this routine is misleading. In particular, this routine need not
block, except when the target process is the calling process.
Implementations may restrict the use of RMA communication that is synchronized
by lock calls to windows in memory allocated by
MPI_Alloc_mem . Locks
can be used portably only in such memory.
The
assert argument is used to indicate special conditions for the fence
that an implementation may use to optimize the
MPI_Win_lock operation.
The value zero is always correct. Other assertion values may be or'ed
together. Assertions that are valid for
MPI_Win_lock 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.
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.
LOCATION¶
/tmp/gyCYfBi4J6/mpich-3.1/src/mpi/rma/win_lock.c