bionic (3) MPI_Iallgatherv.openmpi.3.gz

NAME

       MPI_Allgatherv -  Gathers data from all tasks and deliver the combined data to all tasks

SYNOPSIS

       int MPI_Allgatherv(const void *sendbuf, int sendcount, MPI_Datatype sendtype,
                          void *recvbuf, const int *recvcounts, const int *displs,
                          MPI_Datatype recvtype, MPI_Comm comm)

INPUT PARAMETERS

       sendbuf
              - starting address of send buffer (choice)
       sendcount
              - number of elements in send buffer (integer)
       sendtype
              - data type of send buffer elements (handle)
       recvcounts
              -  integer  array (of length group size) containing the number of elements that are to be received
              from each process
       displs - integer array (of length group size). Entry i specifies the displacement (relative to recvbuf  )
              at which to place the incoming data from process i

       recvtype
              - data type of receive buffer elements (handle)
       comm   - communicator (handle)

OUTPUT PARAMETERS

       recvbuf
              - address of receive buffer (choice)

NOTES

       The MPI standard (1.0 and 1.1) says that

       The  jth block of data sent from each process is received by every process and placed in the jth block of
       the buffer recvbuf .

       This is misleading; a better description is

       The block of data sent from the jth process is received by every process and placed in the jth  block  of
       the buffer recvbuf .

       This  text was suggested by Rajeev Thakur, and has been adopted as a clarification to the MPI standard by
       the MPI-Forum.

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_ERR_BUFFER
              - Invalid buffer pointer.  Usually a null buffer where one is not valid.
       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.  Additionally, this error can occur if  an  uncommitted  MPI_Datatype
              (see MPI_Type_commit ) is used in a communication call.

                                                   11/12/2016                                  MPI_Allgatherv(3)