MPI_Bcast

MPI-MPE

MPI_Bcast

Broadcasts a message from the process with rank "root" to all other processes of the communicator

Synopsis

int MPI_Bcast( void *buffer, int count, MPI_Datatype datatype, int root, 
               MPI_Comm comm )

Input/Output Parameter

buffer
starting address of buffer (choice)

Input Parameters

count
number of entries in buffer (integer)
datatype
data type of buffer (handle)
root
rank of broadcast root (integer)
comm
communicator (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_COMM
Invalid communicator. A common error is to use a null communicator in a call (not even allowed in MPI_Comm_rank).
MPI_ERR_COUNT
Invalid count argument. Count arguments must be non-negative; a count of zero is often valid.
MPI_ERR_TYPE
Invalid datatype argument. May be an uncommitted MPI_Datatype (see MPI_Type_commit).
MPI_ERR_BUFFER
Invalid buffer pointer. Usually a null buffer where one is not valid.
MPI_ERR_ROOT
Invalid root. The root must be specified as a rank in the communicator. Ranks must be between zero and the size of the communicator minus one.

Location:bcast.c