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openmpi/ompi/mpi/c/reduce_scatter.c
Jeff Squyres e8c103ac1f Make MPI_REDUCE and MPI_REDUCE_SCATTER return MPI_SUCCESS immediately
if the count/sum of counts is 0.  This is technically in violation of
the MPI-1 standard, but...  :-(

This commit was SVN r6914.
2005-08-17 15:34:33 +00:00

97 строки
3.1 KiB
C

/*
* Copyright (c) 2004-2005 The Trustees of Indiana University.
* All rights reserved.
* Copyright (c) 2004-2005 The Trustees of the University of Tennessee.
* All rights reserved.
* Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
* University of Stuttgart. All rights reserved.
* Copyright (c) 2004-2005 The Regents of the University of California.
* All rights reserved.
* $COPYRIGHT$
*
* Additional copyrights may follow
*
* $HEADER$
*/
#include "ompi_config.h"
#include <stdio.h>
#include "mpi.h"
#include "datatype/datatype.h"
#include "mpi/c/bindings.h"
#include "mca/coll/coll.h"
#include "errhandler/errhandler.h"
#include "communicator/communicator.h"
#include "op/op.h"
#if OMPI_HAVE_WEAK_SYMBOLS && OMPI_PROFILING_DEFINES
#pragma weak MPI_Reduce_scatter = PMPI_Reduce_scatter
#endif
#if OMPI_PROFILING_DEFINES
#include "mpi/c/profile/defines.h"
#endif
static const char FUNC_NAME[] = "MPI_Reduce_scatter";
int MPI_Reduce_scatter(void *sendbuf, void *recvbuf, int *recvcounts,
MPI_Datatype datatype, MPI_Op op, MPI_Comm comm)
{
int i, err, size, count;
if (MPI_PARAM_CHECK) {
err = MPI_SUCCESS;
OMPI_ERR_INIT_FINALIZE(FUNC_NAME);
if (ompi_comm_invalid(comm)) {
return OMPI_ERRHANDLER_INVOKE(MPI_COMM_WORLD, MPI_ERR_COMM,
FUNC_NAME);
}
/* Unrooted operation; same checks for all ranks on both
intracommunicators and intercommunicators */
else if (MPI_OP_NULL == op) {
err = MPI_ERR_OP;
} else if (ompi_op_is_intrinsic(op) &&
datatype->id < DT_MAX_PREDEFINED &&
-1 == ompi_op_ddt_map[datatype->id]) {
err = MPI_ERR_OP;
} else if (NULL == recvcounts) {
err = MPI_ERR_COUNT;
}
OMPI_ERRHANDLER_CHECK(err, comm, err, FUNC_NAME);
/* We always define the remote group to be the same as the local
group in the case of an intracommunicator, so it's safe to
get the size of the remote group here for both intra- and
intercommunicators */
size = ompi_comm_size(comm);
for (i = 0; i < size; ++i) {
OMPI_CHECK_DATATYPE_FOR_SEND(err, datatype, recvcounts[i]);
OMPI_ERRHANDLER_CHECK(err, comm, err, FUNC_NAME);
}
}
/* MPI-1, p114, says that each process must supply at least one
element. But at least the Pallas benchmarks call MPI_REDUCE
with a count of 0. So be sure to handle it. Grrr... */
size = ompi_comm_size(comm);
for (count = i = 0; i < size; ++i) {
if (0 == recvcounts[i]) {
++count;
}
}
if (size == count) {
return MPI_SUCCESS;
}
/* Invoke the coll component to perform the back-end operation */
err = comm->c_coll.coll_reduce_scatter(sendbuf, recvbuf, recvcounts,
datatype, op, comm);
OMPI_ERRHANDLER_RETURN(err, comm, err, FUNC_NAME);
}