Synopsis

int MPI_Alltoallw(void *sendbuf, int *sendcnts, int *sdispls, 
                  MPI_Datatype *sendtypes, void *recvbuf, int *recvcnts, 
                  int *rdispls, MPI_Datatype *recvtypes, MPI_Comm comm)

Input Parameters

sendbuf

starting address of send buffer (choice)

sendcounts

integer array equal to the group size specifying the number of elements to send to each processor (integer)

sdispls

integer array (of length group size). Entry j specifies the displacement in bytes (relative to sendbuf) from which to take the outgoing data destined for process j

sendtypes

array of datatypes (of length group size). Entry j specifies the type of data to send to process j (handle)

recvcounts

integer array equal to the group size specifying the number of elements that can be received from each processor (integer)

rdispls

integer array (of length group size). Entry i specifies the displacement in bytes (relative to recvbuf) at which to place the incoming data from process i

recvtypes

array of datatypes (of length group size). Entry i specifies the type of data received from process i (handle)

comm

communicator (handle)

Output Parameter

recvbuf

address of receive buffer (choice)

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 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_ARG

Invalid argument. Some argument is invalid and is not identified by a specific error class (e.g., MPI_ERR_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).

Location:alltoallw.c