/* * Copyright (c) 2014 Mellanox Technologies, Inc. * All rights reserved. * $COPYRIGHT$ * * Additional copyrights may follow * * $HEADER$ */ #include #include int main (int argc, char * argv[]) { static int rbuf = -1; int proc, nproc, next, prev; int message = 10; start_pes(0); proc = _my_pe(); nproc = _num_pes(); /* 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; } } /* All done */ printf("Process %d exiting\n", proc); return 0; }