forked from openkylin/openmpi
66 lines
1.7 KiB
C
66 lines
1.7 KiB
C
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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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* $COPYRIGHT$
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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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#include <shmem.h>
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#include <stdio.h>
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#if !defined(OSHMEM_SPEC_VERSION) || OSHMEM_SPEC_VERSION < 10200
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#error This application uses API 1.2 and up
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#endif
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int main (int argc, char * argv[])
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{
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static int rbuf = -1;
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int proc, nproc, next;
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int message = 10;
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shmem_init();
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nproc = shmem_n_pes();
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proc = shmem_my_pe();
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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 = (proc + 1) % nproc;
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if(proc == 0)
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{
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printf("Process 0 puts message %d to %d (%d processes in ring)\n", message, next, nproc);
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shmem_int_put(&rbuf, &message, 1, next);
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}
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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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while(message > 0) {
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shmem_int_wait_until(&rbuf, SHMEM_CMP_EQ, message);
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if(proc == 0) {
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--message;
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printf("Process 0 decremented value: %d\n", message);
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}
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shmem_int_put(&rbuf, &message, 1, next);
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if(proc != 0) {
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--message;
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}
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}
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shmem_finalize();
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/* All done */
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printf("Process %d exiting\n", proc);
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return 0;
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}
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