adding source and scripts for ompi testing scripts

provided scripts:
* ompi_connectivity.sh
* ompi_hello.sh
* ompi_ring.sh

.gitignore

@@ -58,3 +58,15 @@ spool/minos15
 spool/minos26
 spool/minos27
 spool/qmaster/users
+local/examples/src/OpenMPI/connectivity_c
+local/examples/src/OpenMPI/hello_c
+local/examples/src/OpenMPI/hello_cxx
+local/examples/src/OpenMPI/hello_f77
+local/examples/src/OpenMPI/hello_f90
+local/examples/src/OpenMPI/ring_c
+local/examples/src/OpenMPI/ring_cxx
+local/examples/src/OpenMPI/ring_f77
+local/examples/src/OpenMPI/ring_f90
+local/examples/jobsbin/ompi_connectivity_*
+local/examples/jobsbin/ompi_hello_*
+local/examples/jobsbin/ompi_ring_*

examples/jobs/ompi_connectivity.sh

@@ -0,0 +1 @@
+../../local/examples/jobs/ompi_connectivity.sh

examples/jobs/ompi_hello.sh

@@ -0,0 +1 @@
+../../local/examples/jobs/ompi_hello.sh

examples/jobs/ompi_ring.sh

@@ -0,0 +1 @@
+../../local/examples/jobs/ompi_ring.sh

local/examples/jobs/ompi_connectivity.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+# This is a simple example of a SGE batch script
+#$ -pe mpi-rr 4-20
+#$ -l low
+
+# request Bourne shell as shell for job
+#$ -S /bin/bash
+
+#
+# print hostname
+hostname
+# print date and time
+date
+if [ "X$PE_HOSTFILE" != "X" ]; then
+	# print pe_hostfile
+	cat $PE_HOSTFILE
+	# Run ompi_connectivity
+	echo Starting OpenMPI job.
+	mpirun -v /data/gridengine/local/examples/jobsbin/ompi_connectivity_`/usr/bin/lsb_release -cs`
+fi
+# print date and time again
+date

local/examples/jobs/ompi_hello.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+# This is a simple example of a SGE batch script
+#$ -pe mpi-rr 4-20
+#$ -l low
+
+# request Bourne shell as shell for job
+#$ -S /bin/bash
+
+#
+# print hostname
+hostname
+# print date and time
+date
+if [ "X$PE_HOSTFILE" != "X" ]; then
+	# print pe_hostfile
+	cat $PE_HOSTFILE
+	# Run ompi_hello
+	echo Starting OpenMPI job.
+	mpirun -v /data/gridengine/local/examples/jobsbin/ompi_hello_$(/usr/bin/lsb_release -cs)
+fi
+# print date and time again
+date

local/examples/jobs/ompi_ring.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+# This is a simple example of a SGE batch script
+#$ -pe mpi-rr 4-20
+#$ -l low
+
+# request Bourne shell as shell for job
+#$ -S /bin/bash
+
+#
+# print hostname
+hostname
+# print date and time
+date
+if [ "X$PE_HOSTFILE" != "X" ]; then
+	# print pe_hostfile
+	cat $PE_HOSTFILE
+	# Run ompi_ring
+	echo Starting OpenMPI job.
+	mpirun -v /data/gridengine/local/examples/jobsbin/ompi_ring_`/usr/bin/lsb_release -cs`
+fi
+# print date and time again
+date

local/examples/src/OpenMPI/Makefile

@@ -0,0 +1,77 @@
+#
+# Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
+#                         University Research and Technology
+#                         Corporation.  All rights reserved.
+# Copyright (c) 2004-2005 The University of Tennessee and The University
+#                         of Tennessee Research Foundation.  All rights
+#                         reserved.
+# Copyright (c) 2004-2005 High Performance Computing Center Stuttgart, 
+#                         University of Stuttgart.  All rights reserved.
+# Copyright (c) 2004-2005 The Regents of the University of California.
+#                         All rights reserved.
+# Copyright (c) 2006-2007 Sun Microsystems, Inc.  All rights reserved.
+# $COPYRIGHT$
+# 
+# Additional copyrights may follow
+# 
+# $HEADER$
+#
+
+# Use the Open MPI-provided wrapper compilers.  Note that gmake
+# requires the CXX macro, while other versions of make (such as Sun's
+# make) require the CCC macro.
+
+CC = mpicc
+CXX = mpic++
+CCC = mpic++
+F77 = mpif77
+FC = mpif90
+
+# Using -g is not necessary, but it is helpful for example programs,
+# especially if users want to examine them with debuggers.  Note that
+# gmake requires the CXXFLAGS macro, while other versions of make
+# (such as Sun's make) require the CCFLAGS macro.
+
+CFLAGS = -g
+CXXFLAGS = -g
+CCFLAGS = -g
+F77FLAGS = -g
+FCFLAGS = -g
+
+# Example programs to build
+
+EXAMPLES = hello_c hello_cxx hello_f77 hello_f90 \
+           ring_c ring_cxx ring_f77 ring_f90 connectivity_c
+
+# Default target.  Always build the C example.  Only build the others
+# if Open MPI was build with the relevant language bindings.
+
+all: hello_c ring_c connectivity_c
+	@ if test "`ompi_info --parsable | grep bindings:cxx:yes`" != ""; then \
+	    $(MAKE) hello_cxx ring_cxx; \
+	fi
+	@ if test "`ompi_info --parsable | grep bindings:f77:yes`" != ""; then \
+	    $(MAKE) hello_f77 ring_f77; \
+	fi
+	@ if test "`ompi_info --parsable | grep bindings:f90:yes`" != ""; then \
+	    $(MAKE) hello_f90 ring_f90; \
+	fi
+
+
+# The usual "clean" target
+
+clean:
+	rm -f $(EXAMPLES) *~ *.o
+
+# Don't rely on default rules for the fortran examples
+
+hello_f77: hello_f77.f
+	$(F77) $(F77FLAGS) $^ -o $@
+ring_f77: ring_f77.f
+	$(F77) $(F77FLAGS) $^ -o $@
+
+hello_f90: hello_f90.f90
+	$(FC) $(FCFLAGS) $^ -o $@
+ring_f90: ring_f90.f90
+	$(FC) $(FCFLAGS) $^ -o $@
+

local/examples/src/OpenMPI/Makefile.include

@@ -0,0 +1,42 @@
+# -*- makefile -*-
+#
+# Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
+#                         University Research and Technology
+#                         Corporation.  All rights reserved.
+# Copyright (c) 2004-2005 The University of Tennessee and The University
+#                         of Tennessee Research Foundation.  All rights
+#                         reserved.
+# Copyright (c) 2004-2005 High Performance Computing Center Stuttgart, 
+#                         University of Stuttgart.  All rights reserved.
+# Copyright (c) 2004-2005 The Regents of the University of California.
+#                         All rights reserved.
+# Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
+# Copyright (c) 2007      Sun Microsystems, Inc.  All rights reserved.
+# $COPYRIGHT$
+# 
+# Additional copyrights may follow
+# 
+# $HEADER$
+#
+
+# Note that this file does not stand on its own.  It is included by a
+# higher-level Makefile so that Automake features such as "make dist"
+# work properly (and include all the relevant files in this directory
+# in the distribution tarball).
+
+# If you are looking for the file that builds these examples, look at
+# "Makefile" in this same directory (it is *NOT* generated by
+# Automake).
+
+EXTRA_DIST += \
+        examples/README \
+        examples/Makefile \
+        examples/hello_c.c \
+        examples/hello_cxx.cc \
+        examples/hello_f77.f \
+        examples/hello_f90.f90 \
+        examples/ring_c.c \
+        examples/ring_cxx.cc \
+        examples/ring_f77.f \
+        examples/ring_f90.f90 \
+        examples/connectivity_c.c

local/examples/src/OpenMPI/README

@@ -0,0 +1,46 @@
+Copyright (c) 2004-2006 The Trustees of Indiana University and Indiana
+                        University Research and Technology
+                        Corporation.  All rights reserved.
+Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
+Copyright (c) 2007      Sun Microsystems, Inc.  All rights reserved.
+
+The files in this directory are sample MPI applications provided both
+as a trivial primer to MPI as well as simple tests to ensure that your
+Open MPI installation is working properly.
+
+If you are looking for a comprehensive MPI tutorial, these samples are
+not enough.  An excellent MPI tutorial is available here:
+
+        http://webct.ncsa.uiuc.edu:8900/public/MPI/
+
+There are 2 MPI examples in this directory, each in four languages:
+
+- Hello world
+  C:   hello_c.c
+  C++: hello_cxx.cc
+  F77: hello_f77.f
+  F90: hello_f90.f90
+
+- Send a trivial message around in a ring
+  C:   ring_c.c
+  C++: ring_cxx.cc
+  F77: ring_f77.f
+  F90: ring_f90.f90
+
+- Test the connectivity between all processes
+  C:   connectivity_c.c
+
+The Makefile in this directory will build as many of the examples as
+you have language support (e.g., if you do not have F90 bindings
+compiled as part of Open MPI, the F90 examples will be skipped).
+
+The Makefile assumes that the wrapper compilers mpicc, mpic++, mpif77,
+and mpif90 are in your path.
+
+Although the Makefile is tailored for Open MPI (e.g., it checks the
+"ompi_info" command to see if you have support for C++, F77, and F90),
+all of the example programs are pure MPI, and therefore not specific
+to Open MPI.  Hence, you can use a different MPI implementation to
+complie and run these programs if you wish.
+
+Make today an Open MPI day!

local/examples/src/OpenMPI/connectivity_c.c

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2007      Sun Microsystems, Inc.  All rights reserved.
+ */
+
+/*
+ * Test the connectivity between all processes.
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <netdb.h>
+#include <unistd.h>
+#include <mpi.h>
+
+int
+main(int argc, char **argv)
+{
+    MPI_Status  status;
+    int         verbose = 0;
+    int         rank;
+    int         np;        /* number of processes in job */
+    int         peer;
+    int         i;
+    int         j;
+    int         length;
+    char        name[MPI_MAX_PROCESSOR_NAME+1];
+
+    MPI_Init(&argc, &argv);
+    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+    MPI_Comm_size(MPI_COMM_WORLD, &np);
+
+    /*
+     * If we cannot get the name for whatever reason, just
+     * set it to unknown. */
+    if (MPI_SUCCESS != MPI_Get_processor_name(name, &length)) {
+        strcpy(name, "unknown");
+    }
+    
+    if (argc>1 && strcmp(argv[1], "-v")==0)
+        verbose = 1;
+
+    for (i=0; i<np; i++) {
+        if (rank==i) {
+            /* rank i sends to and receives from each higher rank */
+            for(j=i+1; j<np; j++) {
+                if (verbose)
+                    printf("checking connection between rank %d on %s and rank %-4d\n",
+                           i, name, j);
+                MPI_Send(&rank, 1, MPI_INT, j, rank, MPI_COMM_WORLD);
+                MPI_Recv(&peer, 1, MPI_INT, j, j, MPI_COMM_WORLD, &status);
+            }
+        } else if (rank>i) {
+            /* receive from and reply to rank i */
+            MPI_Recv(&peer, 1, MPI_INT, i, i, MPI_COMM_WORLD, &status);
+            MPI_Send(&rank, 1, MPI_INT, i, rank, MPI_COMM_WORLD);
+        }
+    }
+
+    MPI_Barrier(MPI_COMM_WORLD);
+    if (rank==0)
+        printf("Connectivity test on %d processes PASSED.\n", np);
+
+    MPI_Finalize();
+    return 0;
+}

local/examples/src/OpenMPI/hello_c.c

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2004-2006 The Trustees of Indiana University and Indiana
+ *                         University Research and Technology
+ *                         Corporation.  All rights reserved.
+ * Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
+ *
+ * Sample MPI "hello world" application in C
+ */
+
+#include <stdio.h>
+#include "mpi.h"
+
+int main(int argc, char* argv[])
+{
+    int rank, size;
+
+    MPI_Init(&argc, &argv);
+    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+    MPI_Comm_size(MPI_COMM_WORLD, &size);
+    printf("Hello, world, I am %d of %d\n", rank, size);
+    MPI_Barrier(MPI_COMM_WORLD);
+    MPI_Finalize();
+
+    return 0;
+}

local/examples/src/OpenMPI/hello_cxx.cc

@@ -0,0 +1,24 @@
+//
+// Copyright (c) 2004-2006 The Trustees of Indiana University and Indiana
+//                         University Research and Technology
+//                         Corporation.  All rights reserved.
+// Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
+//
+// Sample MPI "hello world" application in C++
+//
+
+#include "mpi.h"
+#include <iostream>
+
+int main(int argc, char **argv)
+{
+    int rank, size;
+
+    MPI::Init();
+    rank = MPI::COMM_WORLD.Get_rank();
+    size = MPI::COMM_WORLD.Get_size();
+    std::cout << "Hello, world!  I am " << rank << " of " << size << std::endl;
+    MPI::Finalize();
+
+    return 0;
+}

local/examples/src/OpenMPI/hello_f77.f

@@ -0,0 +1,20 @@
+C
+C Copyright (c) 2004-2006 The Trustees of Indiana University and Indiana
+C                         University Research and Technology
+C                         Corporation.  All rights reserved.
+C Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
+C
+C Sample MPI "hello world" application in Fortran 77
+C
+        program main
+        implicit none
+        include 'mpif.h'
+        integer ierr, rank, size
+
+        call MPI_INIT(ierr)
+        call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)
+        call MPI_COMM_SIZE(MPI_COMM_WORLD, size, ierr)
+        print *, "Hello, world, I am ", rank, " of ", size
+        call MPI_FINALIZE(ierr)
+
+        end

local/examples/src/OpenMPI/hello_f90.f90

@@ -0,0 +1,21 @@
+!
+! Copyright (c) 2004-2006 The Trustees of Indiana University and Indiana
+!                         University Research and Technology
+!                         Corporation.  All rights reserved.
+! Copyright (c) 2004-2005 The Regents of the University of California.
+!                         All rights reserved.
+! Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
+!
+! Sample MPI "hello world" application in Fortran 90
+!
+program main
+    use mpi
+    implicit none
+    integer :: ierr, rank, size
+
+    call MPI_INIT(ierr)
+    call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)
+    call MPI_COMM_SIZE(MPI_COMM_WORLD, size, ierr)
+    print *, "Hello, world, I am ", rank, " of ", size
+    call MPI_FINALIZE(ierr)
+end

local/examples/src/OpenMPI/install.sh

@@ -0,0 +1,12 @@
+#/bin/bash
+
+# run makefile
+make
+
+# list of executables to install
+files="connectivity_c hello_cxx ring_cxx"
+
+# cp executables to ../../jobsbin
+for file in $files; do
+    cp -p $file ../../jobsbin/ompi_${file%%_c*}_$(lsb_release -cs)
+done

local/examples/src/OpenMPI/ring_c.c

@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2004-2006 The Trustees of Indiana University and Indiana
+ *                         University Research and Technology
+ *                         Corporation.  All rights reserved.
+ * Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
+ *
+ * Simple ring test program
+ */
+
+#include <stdio.h>
+#include "mpi.h"
+
+int main(int argc, char *argv[])
+{
+    int rank, size, next, prev, message, tag = 201;
+
+    /* Start up MPI */
+
+    MPI_Init(&argc, &argv);
+    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+    MPI_Comm_size(MPI_COMM_WORLD, &size);
+ 
+    /* Calculate the rank of the next process in the ring.  Use the
+       modulus operator so that the last process "wraps around" to
+       rank zero. */
+
+    next = (rank + 1) % size;
+    prev = (rank + size - 1) % size;
+
+    /* If we are the "master" process (i.e., MPI_COMM_WORLD rank 0),
+       put the number of times to go around the ring in the
+       message. */
+
+    if (0 == rank) {
+        message = 10;
+
+        printf("Process 0 sending %d to %d, tag %d (%d processes in ring)\n", 
+               message, next, tag, size);
+        MPI_Send(&message, 1, MPI_INT, next, tag, MPI_COMM_WORLD); 
+        printf("Process 0 sent to %d\n", 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 rank 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 (1) {
+        MPI_Recv(&message, 1, MPI_INT, prev, tag, MPI_COMM_WORLD, 
+                 MPI_STATUS_IGNORE);
+
+        if (0 == rank) {
+            --message;
+            printf("Process 0 decremented value: %d\n", message);
+        }
+
+        MPI_Send(&message, 1, MPI_INT, next, tag, MPI_COMM_WORLD);
+        if (0 == message) {
+            printf("Process %d exiting\n", rank);
+            break;
+        }
+    }
+
+    /* The last process does one extra send to process 0, which needs
+       to be received before the program can exit */
+
+    if (0 == rank) {
+        MPI_Recv(&message, 1, MPI_INT, prev, tag, MPI_COMM_WORLD,
+                 MPI_STATUS_IGNORE);
+    }
+    
+    /* All done */
+
+    MPI_Finalize();
+    return 0;
+}

local/examples/src/OpenMPI/ring_cxx.cc

@@ -0,0 +1,78 @@
+//
+// Copyright (c) 2004-2006 The Trustees of Indiana University and Indiana
+//                         University Research and Technology
+//                         Corporation.  All rights reserved.
+// Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
+//
+// Simple ring test program
+//
+
+#include "mpi.h"
+#include <iostream>
+
+int main(int argc, char *argv[])
+{
+    int rank, size, next, prev, message, tag = 201;
+
+    // Start up MPI
+
+    MPI::Init();
+    rank = MPI::COMM_WORLD.Get_rank();
+    size = MPI::COMM_WORLD.Get_size();
+ 
+    // Calculate the rank of the next process in the ring.  Use the
+    // modulus operator so that the last process "wraps around" to
+    // rank zero.
+
+    next = (rank + 1) % size;
+    prev = (rank + size - 1) % size;
+
+    // If we are the "master" process (i.e., MPI_COMM_WORLD rank 0),
+    // put the number of times to go around the ring in the message.
+
+    if (0 == rank) {
+        message = 10;
+
+        std::cout << "Process 0 sending " << message << " to " << next
+                  << ", tag " << tag << " (" << size << " processes in ring)"
+                  << std::endl;
+        MPI::COMM_WORLD.Send(&message, 1, MPI::INT, next, tag);
+        std::cout << "Process 0 sent to " << next << std::endl;
+    }
+
+    // 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 rank 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 (1) {
+        MPI::COMM_WORLD.Recv(&message, 1, MPI::INT, prev, tag);
+
+        if (0 == rank) {
+            --message;
+            std::cout << "Process 0 decremented value: " << message 
+                      << std::endl;
+        }
+
+        MPI::COMM_WORLD.Send(&message, 1, MPI::INT, next, tag);
+        if (0 == message) {
+            std::cout << "Process " << rank << " exiting" << std::endl;
+            break;
+        }
+    }
+
+    // The last process does one extra send to process 0, which needs
+    // to be received before the program can exit */
+
+    if (0 == rank) {
+        MPI::COMM_WORLD.Recv(&message, 1, MPI::INT, prev, tag);
+    }
+    
+    // All done
+
+    MPI::Finalize();
+    return 0;
+}

local/examples/src/OpenMPI/ring_f77.f

@@ -0,0 +1,78 @@
+C
+C Copyright (c) 2004-2006 The Trustees of Indiana University and Indiana
+C                         University Research and Technology
+C                         Corporation.  All rights reserved.
+C Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
+C
+C Simple ring test program
+C
+      program ring_f77
+      implicit none
+      include 'mpif.h'
+      integer rank, size, tag, next, from, message, ierr
+
+C     Start up MPI */
+
+      call MPI_INIT(ierr)
+      call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)
+      call MPI_COMM_SIZE(MPI_COMM_WORLD, size, ierr)
+
+C     Calculate the rank of the next process in the ring.  Use the
+C     modulus operator so that the last process "wraps around" to rank
+C     zero.
+
+      tag = 201
+      next = mod((rank + 1), size)
+      from = mod((rank + size - 1), size)
+      
+C     If we are the "master" process (i.e., MPI_COMM_WORLD rank 0), put
+C     the number of times to go around the ring in the message.
+
+      if (rank .eq. 0) then
+         message = 10
+
+         print *, 'Process 0 sending ', message, ' to ', next, ' tag ',
+     &        tag, ' (', size, ' processes in ring)'
+         call MPI_SEND(message, 1, MPI_INTEGER, next, tag, 
+     &        MPI_COMM_WORLD, ierr)
+         print *, 'Process 0 sent to ', next
+      endif
+
+C     Pass the message around the ring.  The exit mechanism works as
+C     follows: the message (a positive integer) is passed around the
+C     ring.  Each time it passes rank 0, it is decremented.  When each
+C     processes receives a message containing a 0 value, it passes the
+C     message on to the next process and then quits.  By passing the 0
+C     message first, every process gets the 0 message and can quit
+C     normally.
+
+ 10   call MPI_RECV(message, 1, MPI_INTEGER, from, tag, 
+     &     MPI_COMM_WORLD, MPI_STATUS_IGNORE, ierr)
+
+      if (rank .eq. 0) then
+         message = message - 1
+         print *, 'Process 0 decremented value:', message
+      endif
+
+      call MPI_SEND(message, 1, MPI_INTEGER, next, tag, 
+     &     MPI_COMM_WORLD, ierr)
+      
+      if (message .eq. 0) then
+         print *, 'Process ', rank, ' exiting'
+         goto 20
+      endif
+      goto 10
+
+C     The last process does one extra send to process 0, which needs to
+C     be received before the program can exit
+
+ 20   if (rank .eq. 0) then
+         call MPI_RECV(message, 1, MPI_INTEGER, from, tag, 
+     &        MPI_COMM_WORLD, MPI_STATUS_IGNORE, ierr)
+      endif
+
+C     All done
+
+      call MPI_FINALIZE(ierr)
+      end
+      

local/examples/src/OpenMPI/ring_f90.f90

@@ -0,0 +1,73 @@
+!
+! Copyright (c) 2004-2006 The Trustees of Indiana University and Indiana
+!                         University Research and Technology
+!                         Corporation.  All rights reserved.
+! Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
+!
+! Simple ring test program
+!
+program ring
+  use mpi
+  implicit none
+  integer :: rank, size, tag, next, from, message, ierr
+
+! Start up MPI
+
+  call MPI_INIT(ierr)
+  call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)
+  call MPI_COMM_SIZE(MPI_COMM_WORLD, size, ierr)
+
+! Calculate the rank of the next process in the ring.  Use the modulus
+! operator so that the last process "wraps around" to rank zero.
+
+  tag = 201
+  next = mod((rank + 1), size)
+  from = mod((rank + size - 1), size)
+      
+! If we are the "master" process (i.e., MPI_COMM_WORLD rank 0), put
+! the number of times to go around the ring in the message.
+
+  if (rank .eq. 0) then
+     message = 10
+
+     print *, 'Process 0 sending ', message, ' to ', next, ' tag ', tag, ' (', size, ' processes in ring)'
+     call MPI_SEND(message, 1, MPI_INTEGER, next, tag, MPI_COMM_WORLD, ierr)
+     print *, 'Process 0 sent to ', next
+  endif
+
+! 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 rank 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.
+
+10 call MPI_RECV(message, 1, MPI_INTEGER, from, tag, MPI_COMM_WORLD, &
+        MPI_STATUS_IGNORE, ierr)
+
+  if (rank .eq. 0) then
+     message = message - 1
+     print *, 'Process 0 decremented value:', message
+  endif
+
+  call MPI_SEND(message, 1, MPI_INTEGER, next, tag, MPI_COMM_WORLD, ierr)
+      
+  if (message .eq. 0) then
+     print *, 'Process ', rank, ' exiting'
+     goto 20
+  endif
+  goto 10
+
+! The last process does one extra send to process 0, which needs to be
+! received before the program can exit
+
+ 20 if (rank .eq. 0) then
+     call MPI_RECV(message, 1, MPI_INTEGER, from, tag, MPI_COMM_WORLD, &
+          MPI_STATUS_IGNORE, ierr)
+  endif
+
+! All done
+
+  call MPI_FINALIZE(ierr)
+end program
+