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/*
* Copyright (c) 2014 Mellanox Technologies, Inc.
* All rights reserved.
* $COPYRIGHT$
*
* Additional copyrights may follow
*
* $HEADER$
*/
#include <shmem.h>
#include <stdio.h>
#if !defined(OSHMEM_SPEC_VERSION) || OSHMEM_SPEC_VERSION < 10200
#error This application uses API 1.2 and up
#endif
int main (int argc, char * argv[])
{
static int rbuf = -1;
int proc, nproc, next;
int message = 10;
shmem_init();
nproc = shmem_n_pes();
proc = shmem_my_pe();
/* Calculate the PE number of the next process in the ring. Use the
modulus operator so that the last process "wraps around" to PE 0. */
next = (proc + 1) % nproc;
if(proc == 0)
{
printf("Process 0 puts message %d to %d (%d processes in ring)\n", message, next, nproc);
shmem_int_put(&rbuf, &message, 1, next);
}
/* Pass the message around the ring. The exit mechanism works as
follows: the message (a positive integer) is passed around the
ring. Each time it passes PE 0, it is decremented. When each
processes receives a message containing a 0 value, it passes the
message on to the next process and then quits. By passing the 0
message first, every process gets the 0 message and can quit
normally. */
while(message > 0) {
shmem_int_wait_until(&rbuf, SHMEM_CMP_EQ, message);
if(proc == 0) {
--message;
printf("Process 0 decremented value: %d\n", message);
}
shmem_int_put(&rbuf, &message, 1, next);
if(proc != 0) {
--message;
}
}
shmem_finalize();
/* All done */
printf("Process %d exiting\n", proc);
return 0;
}
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