root / synthbench / euroben-dm / mod1h / .svn / text-base / nearn_1d.f.svn-base @ 0:839f52ef7657
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Subroutine nearn_1d( title, me, npes, nrpt, ncases, n, tn, |
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& ops ) |
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! ---------------------------------------------------------------------- |
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Use numerics |
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Use max_params |
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Implicit None |
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Include 'mpif.h' |
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Character*50 :: title |
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Integer :: me, npes, nrpt, ncases, n |
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Real(l_) :: tn(maxcases), ops, timer |
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Real(l_) :: a(nmax), b(nmax), c(nmax) |
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Real(l_) :: buffer( 8*(nmax + MPI_Bsend_Overhead/8 )) |
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Real(l_) :: t1, t2 |
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Integer :: k, tag |
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Integer :: comm, commcart, ie, type |
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Integer :: status(MPI_Status_Size) |
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Integer, Parameter :: dim = 1 |
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Integer :: dims(dim) |
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Integer :: pos(dim) |
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Logical :: periods(dim) |
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Integer :: moi, myid |
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Integer :: west, east |
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Integer :: size |
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Save a, b, c |
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! ---------------------------------------------------------------------- |
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comm = MPI_Comm_World |
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type = MPI_Real8 |
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title = ' N PEs <-- 2N PEs; Nearst nbr 1D' |
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nrpt = 100 |
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ncases = npes |
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ops = 2*8*n |
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size = 8*n |
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tn(1:maxcases) = 1.0e-15_l_ |
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periods = .TRUE. ! --- Introduce topology |
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dims = 0 |
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Call MPI_Comm_Rank( comm, myid, ie) |
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Call MPI_Dims_Create( npes, dim, dims, ie ) |
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Call MPI_Cart_Create( comm, dim, dims, periods, .TRUE., |
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& commcart, ie ) |
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! --- Get position and rank in Cartesian grid. |
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Call MPI_Cart_Get( commcart, dim, dims, periods, pos, ie ) |
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Call MPI_Cart_Rank( commcart, pos, moi, ie ) |
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Call MPI_Buffer_Attach(buffer, 8*(size+MPI_Bsend_Overhead), ie ) |
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! --- Get rank of neighbours. |
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Call MPI_Cart_Coords( commcart, myid, dim, dims, ie ) |
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Call MPI_Cart_Shift( commcart, 0, -1, myid, west, ie ) |
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Call MPI_Cart_Shift( commcart, 0, 1, myid, east, ie ) |
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Call MPI_Barrier( commcart, ie ) |
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t1 = timer() |
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Do k = 1, nrpt |
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tag = (k * npes * 2) |
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Call MPI_Bsend( a, n, type, west, tag + moi, commcart, ie ) |
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Call MPI_Bsend( a, n, type, east, tag + moi + 1,commcart, ie ) |
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Call MPI_Recv( b, n, type, west, tag + west + 1, |
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& commcart, status, ie ) |
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Call MPI_Recv( c, n, type, east, tag + east, |
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& commcart, status, ie ) |
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End Do |
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t2 = timer() |
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tn (myid+1) = Max( 1.0e-15_l_, (t2-t1) / (2*nrpt) ) |
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Call MPI_Buffer_Detach( buffer, size, ie ) |
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! ---------------------------------------------------------------------- |
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End Subroutine nearn_1d |