72 строки
2.7 KiB
C
72 строки
2.7 KiB
C
/*
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* Copyright (c) 2004-2005 The Regents of the University of California.
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* All rights reserved.
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* Copyright (c) 2004-2006 The University of Tennessee and The University
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* of Tennessee Research Foundation. All rights
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* reserved.
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* Copyright (c) 2006 Cisco Systems, Inc. All rights reserved.
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* Copyright (c) 2007 Los Alamos National Security, LLC. All rights
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* reserved.
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* Copyright (c) 2016 Intel, Inc. All rights reserved.
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* Copyright (c) 2017 Research Organization for Information Science
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* and Technology (RIST). All rights reserved.
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* $COPYRIGHT$
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*
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* Additional copyrights may follow
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*
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* $HEADER$
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*/
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#include "ompi_config.h"
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#include <stdlib.h>
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#include "ompi/constants.h"
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#include "ompi/mca/pml/pml.h"
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#include "ompi/communicator/communicator.h"
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#include "ompi/runtime/mpiruntime.h"
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#include "ompi/mca/coll/base/coll_base_util.h"
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int
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ompi_init_preconnect_mpi(void)
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{
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int comm_size = ompi_comm_size(MPI_COMM_WORLD);
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int comm_rank = ompi_comm_rank(MPI_COMM_WORLD);
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int param, next, prev, i, ret = OMPI_SUCCESS;
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char inbuf[1], outbuf[1];
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const bool *value = NULL;
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param = mca_base_var_find("ompi", "mpi", NULL, "preconnect_mpi");
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if (0 > param) return OMPI_SUCCESS;
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ret = mca_base_var_get_value(param, &value, NULL, NULL);
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if (OMPI_SUCCESS != ret || (NULL != value && 0 == value[0])) {
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return OMPI_SUCCESS;
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}
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inbuf[0] = outbuf[0] = '\0';
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/* Each iteration, every process sends to its neighbor i hops to
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the right and receives from its neighbor i hops to the left.
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Because send_complete is used, there will only ever be one
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outstanding send and one outstanding receive in the network at
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a time for any given process. This limits any "flooding"
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effect that can occur with other connection algorithms. While
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the flooding algorithms may be a more efficient use of
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resources, they can overwhelm the out-of-band connection system
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used to wire up some networks, leading to poor performance and
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hangs. */
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for (i = 1 ; i <= comm_size / 2 ; ++i) {
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next = (comm_rank + i) % comm_size;
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prev = (comm_rank - i + comm_size) % comm_size;
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ret = ompi_coll_base_sendrecv_actual(outbuf, 1, MPI_CHAR,
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next, 1,
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inbuf, 1, MPI_CHAR,
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prev, 1,
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MPI_COMM_WORLD, MPI_STATUS_IGNORE);
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if(OMPI_SUCCESS != ret) return ret;
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}
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return ret;
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}
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