NAME¶
MPI_Win_allocate_shared - Create an MPI Window object for one-sided
communication and shared memory access, and allocate memory at each process.
SYNOPSIS¶
int MPI_Win_allocate_shared(MPI_Aint size, int disp_unit, MPI_Info info, MPI_Comm comm,
void *baseptr, MPI_Win *win)
This is a collective call executed by all processes in the group of comm. On
each process i, it allocates memory of at least size bytes that is shared
among all processes in comm, and returns a pointer to the locally allocated
segment in baseptr that can be used for load/store accesses on the calling
process. The locally allocated memory can be the target of load/store accesses
by remote processes; the base pointers for other processes can be queried
using the function
MPI_Win_shared_query .
The call also returns a window object that can be used by all processes in comm
to perform RMA operations. The size argument may be different at each process
and size = 0 is valid. It is the user's responsibility to ensure that the
communicator comm represents a group of processes that can create a shared
memory segment that can be accessed by all processes in the group. The
allocated memory is contiguous across process ranks unless the info key
alloc_shared_noncontig is specified. Contiguous across process ranks means
that the first address in the memory segment of process i is consecutive with
the last address in the memory segment of process i − 1. This may
enable the user to calculate remote address offsets with local information
only.
- size
- - size of window in bytes (nonnegative integer)
- disp_unit
- - local unit size for displacements, in bytes (positive integer)
- info
- - info argument (handle)
- comm
- - communicator (handle)
OUTPUT PARAMETERS¶
- baseptr
- - initial address of window (choice)
- win
- - window object returned by the call (handle)
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_COMM
- - Invalid communicator. A common error is to use a null communicator in a
call (not even allowed in MPI_Comm_rank ).
- MPI_ERR_INFO
- - Invalid Info
- MPI_ERR_OTHER
- - Other error; use MPI_Error_string to get more information about
this error code.
- MPI_ERR_SIZE
- -
SEE ALSO¶
MPI_Win_allocate MPI_Win_create MPI_Win_create_dynamic MPI_Win_free
MPI_Win_shared_query
LOCATION¶
/tmp/gyCYfBi4J6/mpich-3.1/src/mpi/rma/win_allocate_shared.c