4b4dbda0df
bindings by default. Fix a typo in README, and add a bullet to news about the MPI C++ bindings. This commit was SVN r27948.
86 строки
2.7 KiB
C++
86 строки
2.7 KiB
C++
//
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// Copyright (c) 2004-2006 The Trustees of Indiana University and Indiana
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// University Research and Technology
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// Corporation. All rights reserved.
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// Copyright (c) 2006 Cisco Systems, Inc. All rights reserved.
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//
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// Simple ring test program
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//
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// NOTE: The MPI C++ bindings were deprecated in MPI-2.2 and removed
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// from the standard in MPI-3. Open MPI still provides C++ MPI
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// bindings, but they are no longer built by default (and may be
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// removed in a future version of Open MPI). You must
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// --enable-mpi-cxx when configuring Open MPI to enable the MPI C++
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// bindings.
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//
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#include "mpi.h"
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#include <iostream>
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int main(int argc, char *argv[])
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{
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int rank, size, next, prev, message, tag = 201;
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// Start up MPI
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MPI::Init();
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rank = MPI::COMM_WORLD.Get_rank();
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size = MPI::COMM_WORLD.Get_size();
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// Calculate the rank of the next process in the ring. Use the
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// modulus operator so that the last process "wraps around" to
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// rank zero.
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next = (rank + 1) % size;
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prev = (rank + size - 1) % size;
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// If we are the "master" process (i.e., MPI_COMM_WORLD rank 0),
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// put the number of times to go around the ring in the message.
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if (0 == rank) {
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message = 10;
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std::cout << "Process 0 sending " << message << " to " << next
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<< ", tag " << tag << " (" << size << " processes in ring)"
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<< std::endl;
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MPI::COMM_WORLD.Send(&message, 1, MPI::INT, next, tag);
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std::cout << "Process 0 sent to " << next << std::endl;
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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 rank 0, it is decremented. When
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// each processes receives a message containing a 0 value, it
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// passes the message on to the next process and then quits. By
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// passing the 0 message first, every process gets the 0 message
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// and can quit normally.
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while (1) {
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MPI::COMM_WORLD.Recv(&message, 1, MPI::INT, prev, tag);
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if (0 == rank) {
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--message;
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std::cout << "Process 0 decremented value: " << message
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<< std::endl;
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}
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MPI::COMM_WORLD.Send(&message, 1, MPI::INT, next, tag);
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if (0 == message) {
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std::cout << "Process " << rank << " exiting" << std::endl;
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break;
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}
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}
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// The last process does one extra send to process 0, which needs
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// to be received before the program can exit */
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if (0 == rank) {
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MPI::COMM_WORLD.Recv(&message, 1, MPI::INT, prev, tag);
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}
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// All done
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MPI::Finalize();
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return 0;
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}
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