110 строки
3.3 KiB
C
110 строки
3.3 KiB
C
/*
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* Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
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* University Research and Technology
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* Corporation. All rights reserved.
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* Copyright (c) 2004-2005 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) 2004-2005 High Performance Computing Center Stuttgart,
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* University of Stuttgart. All rights reserved.
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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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* $COPYRIGHT$
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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 "mca/topo/base/base.h"
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#include "communicator/communicator.h"
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#include "mca/topo/topo.h"
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/*
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* function - Returns the shifted source and destination ranks, given a
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* shift direction and amount
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*
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* @param comm communicator with cartesian structure (handle)
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* @param direction coordinate directionension of shift (integer)
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* @param disp displacement (> 0: upwards shift, < 0: downwards shift) (integer)
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* @param rank_source rank of source process (integer)
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* @param rank_dest rank of destination process (integer)
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*
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* The 'direction' argument is in the range '[0,n-1]' for an n-directionensional
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* Cartesian mesh.
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*
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* @retval MPI_SUCCESS
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* @retval MPI_ERR_TOPOLOGY
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* @retval MPI_ERR_DIMS
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* @retval MPI_ERR_COMM
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* @retval MPI_ERR_ARG
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*/
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int mca_topo_base_cart_shift (MPI_Comm comm,
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int direction,
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int disp,
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int *rank_source,
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int *rank_dest){
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int factor;
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int thisdirection = 0;
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int thisperiod = 0;
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int ord;
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int srcord;
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int destord;
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int i;
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int *p;
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/*
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* Handle the trivial case.
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*/
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ord = ompi_comm_rank(comm);
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if (disp == 0) {
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*rank_dest = *rank_source = ord;
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return MPI_SUCCESS;
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}
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/*
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* Compute the rank factor and ordinate.
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*/
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factor = ompi_comm_size(comm);
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p = comm->c_topo_comm->mtc_dims_or_index;
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for (i = 0; (i < comm->c_topo_comm->mtc_ndims_or_nnodes) && (i <= direction); ++i, ++p) {
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if ((thisdirection = *p) > 0) {
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thisperiod = 0;
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} else {
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thisperiod = 1;
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thisdirection = -thisdirection;
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}
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ord %= factor;
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factor /= thisdirection;
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}
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ord /= factor;
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/*
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* Check the displacement value and compute the new ranks.
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*/
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*rank_source = *rank_dest = MPI_UNDEFINED;
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srcord = ord - disp;
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destord = ord + disp;
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if ( ((destord < 0) || (destord >= thisdirection)) && (!thisperiod) ) {
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*rank_dest = MPI_PROC_NULL;
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} else {
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destord %= thisdirection;
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if (destord < 0) destord += thisdirection;
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*rank_dest = ompi_comm_rank(comm);
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*rank_dest += ((destord - ord) * factor);
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}
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if ( ((srcord < 0) || (srcord >= thisdirection)) && (!thisperiod) ) {
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*rank_source = MPI_PROC_NULL;
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} else {
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srcord %= thisdirection;
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if (srcord < 0) srcord += thisdirection;
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*rank_source= ompi_comm_rank(comm);
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*rank_source += ((srcord - ord) * factor);
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}
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return MPI_SUCCESS;
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}
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