root / src / grid / HPL_reduce.c
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/*
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* -- High Performance Computing Linpack Benchmark (HPL)
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* HPL - 2.0 - September 10, 2008
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* Antoine P. Petitet
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* University of Tennessee, Knoxville
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* Innovative Computing Laboratory
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* (C) Copyright 2000-2008 All Rights Reserved
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*
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* -- Copyright notice and Licensing terms:
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions, and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. All advertising materials mentioning features or use of this
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* software must display the following acknowledgement:
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* This product includes software developed at the University of
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* Tennessee, Knoxville, Innovative Computing Laboratory.
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*
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* 4. The name of the University, the name of the Laboratory, or the
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* names of its contributors may not be used to endorse or promote
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* products derived from this software without specific written
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* permission.
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*
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* -- Disclaimer:
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY
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* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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* ---------------------------------------------------------------------
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*/
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/*
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* Include files
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*/
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#include "hpl.h" |
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#ifdef STDC_HEADERS
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int HPL_reduce
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( |
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void * BUFFER,
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const int COUNT, |
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const HPL_T_TYPE DTYPE,
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const HPL_T_OP OP,
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const int ROOT, |
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MPI_Comm COMM |
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) |
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#else
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int HPL_reduce
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( BUFFER, COUNT, DTYPE, OP, ROOT, COMM ) |
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void * BUFFER;
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const int COUNT; |
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const HPL_T_TYPE DTYPE;
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const HPL_T_OP OP;
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const int ROOT; |
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MPI_Comm COMM; |
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#endif
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{ |
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/*
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* Purpose
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* =======
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*
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* HPL_reduce performs a global reduce operation across all processes of
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* a group. Note that the input buffer is used as workarray and in all
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* processes but the accumulating process corrupting the original data.
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*
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* Arguments
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* =========
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*
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* BUFFER (local input/output) void *
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* On entry, BUFFER points to the buffer to be reduced. On
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* exit, and in process of rank ROOT this array contains the
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* reduced data. This buffer is also used as workspace during
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* the operation in the other processes of the group.
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*
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* COUNT (global input) const int
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* On entry, COUNT indicates the number of entries in BUFFER.
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* COUNT must be at least zero.
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*
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* DTYPE (global input) const HPL_T_TYPE
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* On entry, DTYPE specifies the type of the buffers operands.
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*
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* OP (global input) const HPL_T_OP
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* On entry, OP is a pointer to the local combine function.
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*
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* ROOT (global input) const int
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* On entry, ROOT is the coordinate of the accumulating process.
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*
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* COMM (global/local input) MPI_Comm
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* The MPI communicator identifying the process collection.
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*
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* ---------------------------------------------------------------------
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*/
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/*
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* .. Local Variables ..
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*/
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MPI_Status status; |
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void * buffer = NULL; |
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int hplerr=MPI_SUCCESS, d=1, i, ip2=1, mask=0, |
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mpierr, mydist, partner, rank, size, |
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tag = MSGID_BEGIN_COLL; |
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/* ..
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* .. Executable Statements ..
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*/
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if( COUNT <= 0 ) return( MPI_SUCCESS ); |
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mpierr = MPI_Comm_size( COMM, &size ); |
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if( size == 1 ) return( MPI_SUCCESS ); |
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mpierr = MPI_Comm_rank( COMM, &rank ); |
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i = size - 1; while( i > 1 ) { i >>= 1; d++; } |
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if( DTYPE == HPL_INT )
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buffer = (void *)( (int *) malloc( (size_t)(COUNT) * |
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sizeof( int ) ) ); |
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else
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buffer = (void *)( (double *)malloc( (size_t)(COUNT) * |
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sizeof( double ) ) ); |
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if( !( buffer ) )
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{ HPL_pabort( __LINE__, "HPL_reduce", "Memory allocation failed" ); } |
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if( ( mydist = MModSub( rank, ROOT, size ) ) == 0 ) |
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{ |
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do
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{ |
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mpierr = MPI_Recv( buffer, COUNT, HPL_2_MPI_TYPE( DTYPE ), |
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MModAdd( ROOT, ip2, size ), tag, COMM, |
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&status ); |
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if( mpierr != MPI_SUCCESS ) hplerr = mpierr;
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OP( COUNT, buffer, BUFFER, DTYPE ); |
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ip2 <<= 1; d--;
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} while( d );
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} |
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else
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{ |
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do
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{ |
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if( ( mydist & mask ) == 0 ) |
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{ |
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partner = mydist ^ ip2; |
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if( mydist & ip2 )
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{ |
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partner = MModAdd( ROOT, partner, size ); |
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mpierr = MPI_Send( BUFFER, COUNT, HPL_2_MPI_TYPE( DTYPE ), |
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partner, tag, COMM ); |
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} |
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else if( partner < size ) |
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{ |
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partner = MModAdd( ROOT, partner, size ); |
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mpierr = MPI_Recv( buffer, COUNT, HPL_2_MPI_TYPE( DTYPE ), |
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partner, tag, COMM, &status ); |
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OP( COUNT, buffer, BUFFER, DTYPE ); |
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} |
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if( mpierr != MPI_SUCCESS ) hplerr = mpierr;
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} |
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mask ^= ip2; ip2 <<= 1; d--;
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} while( d );
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} |
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if( buffer ) free( buffer );
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return( hplerr );
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/*
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* End of HPL_reduce
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*/
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} |