| 1 | subroutine MPP_REDUCE_( a, pelist ) |
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| 2 | !find the max of scalar a the PEs in pelist (all PEs if this argument is omitted) |
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| 3 | !result is also automatically broadcast to all PEs |
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| 4 | MPP_TYPE_, intent(inout) :: a |
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| 5 | integer, intent(in), optional :: pelist(0:) |
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| 6 | integer :: n |
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| 7 | #ifdef use_libSMA |
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| 8 | !work holds pWrk array + 1 word for symmetric copy of a |
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| 9 | MPP_TYPE_ :: work(SHMEM_REDUCE_MIN_WRKDATA_SIZE+1) |
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| 10 | pointer( ptr, work ) |
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| 11 | integer :: words |
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| 12 | character(len=8) :: text |
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| 13 | #endif /* use_libSMA */ |
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| 14 | #ifdef use_libMPI |
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| 15 | MPP_TYPE_ :: work |
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| 16 | #endif |
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| 17 | if( .NOT.module_is_initialized )call mpp_error( FATAL, 'MPP_REDUCE: You must first call mpp_init.' ) |
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| 18 | n = get_peset(pelist); if( peset(n)%count.EQ.1 )return |
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| 19 | |
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| 20 | if( current_clock.NE.0 )call SYSTEM_CLOCK(start_tick) |
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| 21 | #ifdef use_libSMA |
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| 22 | !allocate space from the stack for pwrk and b |
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| 23 | ptr = LOC(mpp_stack) |
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| 24 | words = size(work)*size(transfer(work(1),word)) |
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| 25 | if( words.GT.mpp_stack_size )then |
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| 26 | write( text, '(i8)' )words |
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| 27 | call mpp_error( FATAL, 'MPP_REDUCE user stack overflow: call mpp_set_stack_size('//text//') from all PEs.' ) |
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| 28 | end if |
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| 29 | mpp_stack_hwm = max( words, mpp_stack_hwm ) |
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| 30 | |
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| 31 | work(1) = a |
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| 32 | call SHMEM_REDUCE_( work, work, 1, peset(n)%start, peset(n)%log2stride, peset(n)%count, work(2), sync ) |
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| 33 | call mpp_sync(pelist) |
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| 34 | a = work(1) |
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| 35 | #endif /* use_libSMA */ |
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| 36 | #ifdef use_libMPI |
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| 37 | if( verbose )call mpp_error( NOTE, 'MPP_REDUCE_: using MPI_ALLREDUCE...' ) |
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| 38 | call MPI_ALLREDUCE( a, work, 1, MPI_TYPE_, MPI_REDUCE_, peset(n)%id, error ) |
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| 39 | a = work |
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| 40 | #endif |
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| 41 | if( current_clock.NE.0 )call increment_current_clock( EVENT_ALLREDUCE, MPP_TYPE_BYTELEN_ ) |
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| 42 | return |
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| 43 | end subroutine MPP_REDUCE_ |
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