forked from openkylin/openmpi
67 lines
1.8 KiB
Fortran
67 lines
1.8 KiB
Fortran
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!
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! Copyright (c) 2014 Mellanox Technologies, Inc.
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! All rights reserved.
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! Copyright (c) 2014 Cisco Systems, Inc. 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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program ring_oshmem
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implicit none
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include 'shmem.fh'
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integer*8, save :: rbuf
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integer*8 :: message
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integer :: proc, nproc, next
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integer :: my_pe, num_pes
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rbuf = -1
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message = 10
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call start_pes(0)
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proc = my_pe()
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nproc = num_pes()
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! Calculate the PE number of the next process in the ring. Use the
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! modulus operator so that the last process "wraps around" to PE 0.
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next = mod((proc + 1), nproc)
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if (proc .eq. 0) then
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write(*, '("Process 0 sending ", i2, " to", i2, " (", i2, " processes in ring)")') message, next, nproc
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call shmem_put8(rbuf, message, 1, next)
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write(*, '("Process 0 sent to ", i2)') next
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end if
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! Pass the message around the ring. The exit mechanism works as
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! follows: the message (a positive integer) is passed around the
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! ring. Each time it passes PE 0, it is decremented. When each
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! processes receives a message containing a 0 value, it passes the
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! message on to the next process and then quits. By passing the 0
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! message first, every process gets the 0 message and can quit
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! normally.
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do while (message .gt. 0)
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call shmem_int8_wait_until(rbuf, SHMEM_CMP_EQ, message)
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if (proc .eq. 0) then
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message = message - 1
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write(*, '("Process 0 decremented value:", i2)') message
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end if
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call shmem_put8(rbuf, message, 1, next)
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if (proc .gt. 0) then
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message = message - 1
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end if
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end do
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! All done
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write(*, '("Process", i2," exiting.")') proc
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end program ring_oshmem
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