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59 lines
1.0 KiB
59 lines
1.0 KiB
program mpigatherinplace
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use mpi
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implicit none
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integer :: rank, ierr, nmpi, i
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integer :: N, err
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real(kind=8), dimension(:), allocatable :: allx
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real :: asum, lsum
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N = 128*1024*1024
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call MPI_Init(ierr)
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if (ierr /= 0) then
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print *, 'Failed MPI_Init: ', ierr
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stop
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end if
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call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)
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if (ierr /= 0) then
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print *, 'Failed MPI_COMM_RANK: ', ierr
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stop
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end if
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call MPI_COMM_SIZE(MPI_COMM_WORLD, nmpi, ierr)
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if (ierr /= 0) then
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print *, 'Failed MPI_COMM_SIZE: ', ierr
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stop
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end if
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allocate(allx(N*nmpi))
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lsum = 0
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do i=1, N
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allx(rank*N+i) = rank*i/N
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lsum = lsum + allx(rank*N+i)
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end do
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call MPI_Allgather(MPI_IN_PLACE, 0, MPI_DOUBLE, &
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& allx, N, MPI_DOUBLE, MPI_COMM_WORLD, ierr)
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if (ierr /= 0) then
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print *, 'Failed MPI_Allgather: ', ierr
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stop
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end if
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asum = sum(allx)
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print *, rank, "/", nmpi, " ", lsum, " ", asum
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deallocate(allx)
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call MPI_Finalize(ierr)
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if (ierr /= 0) then
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print *, 'Failed MPI_Finalize: ', ierr
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stop
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end if
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end program mpigatherinplace
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