MPI_Win_allocate_shared(3) MPI MPI_Win_allocate_shared(3)
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)
int MPI_Win_allocate_shared_c(MPI_Aint size, MPI_Aint disp_unit, MPI_Info info,
MPI_Comm comm, void *baseptr, MPI_Win *win)
INPUT PARAMETERS
size - size of local window in bytes (non-negative integer)
disp_unit
- local unit size for displacements, in bytes (positive integer)
info - info argument (handle)
comm - intra-communicator (handle)
OUTPUT PARAMETERS
baseptr
- address of local allocated window segment (choice)
win - window object returned by the call (handle)
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.
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
guarantee 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_DISP
-
MPI_ERR_INFO
- Invalid Info
MPI_ERR_SIZE
-
MPI_ERR_OTHER
- Other error; use MPI_Error_string to get more information about
this error code.
SEE ALSO
MPI_Win_allocate MPI_Win_create MPI_Win_create_dynamic MPI_Win_free
MPI_Win_shared_query
1/27/2023 MPI_Win_allocate_shared(3)
mpi 4.1 - Generated Sat Jan 28 18:12:44 CST 2023