84 строки
3.0 KiB
C
84 строки
3.0 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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* $COPYRIGHT$
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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/request/request.h"
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#include "ompi/runtime/mpiruntime.h"
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#include "ompi/mca/dpm/dpm.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, value, next, prev, i, ret = OMPI_SUCCESS;
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struct ompi_request_t * requests[2];
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char inbuf[1], outbuf[1];
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param = mca_base_param_find("mpi", NULL, "preconnect_mpi");
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if (OMPI_ERROR == param) return OMPI_SUCCESS;
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ret = mca_base_param_lookup_int(param, &value);
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if (OMPI_SUCCESS != ret) return OMPI_SUCCESS;
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if (0 == value) {
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param = mca_base_param_find("mpi", NULL, "preconnect_all");
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if (OMPI_ERROR == param) return OMPI_SUCCESS;
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ret = mca_base_param_lookup_int(param, &value);
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if (OMPI_SUCCESS != ret) return OMPI_SUCCESS;
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}
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if (0 == value) return OMPI_SUCCESS;
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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 = MCA_PML_CALL(isend(outbuf, 1, MPI_CHAR,
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next, 1,
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MCA_PML_BASE_SEND_COMPLETE,
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MPI_COMM_WORLD,
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&requests[1]));
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if (OMPI_SUCCESS != ret) return ret;
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ret = MCA_PML_CALL(irecv(inbuf, 1, MPI_CHAR,
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prev, 1,
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MPI_COMM_WORLD,
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&requests[0]));
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if(OMPI_SUCCESS != ret) return ret;
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ret = ompi_request_wait_all(2, requests, MPI_STATUSES_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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