1.. Copyright (C) 2004-2009 The Trustees of Indiana University. 2 Use, modification and distribution is subject to the Boost Software 3 License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at 4 http://www.boost.org/LICENSE_1_0.txt) 5 6============================ 7|Logo| MPI BSP Process Group 8============================ 9 10.. contents:: 11 12Introduction 13------------ 14 15The MPI ``mpi_process_group`` is an implementation of the `process 16group`_ interface using the Message Passing Interface (MPI). It is the 17primary process group used in the Parallel BGL at this time. 18 19Where Defined 20------------- 21 22Header ``<boost/graph/distributed/mpi_process_group.hpp>`` 23 24Reference 25--------- 26 27:: 28 29 namespace boost { namespace graph { namespace distributed { 30 31 class mpi_process_group 32 { 33 public: 34 typedef boost::mpi::communicator communicator_type; 35 36 // Process group constructors 37 mpi_process_group(communicator_type comm = communicator_type()); 38 mpi_process_group(std::size_t num_headers, std::size_t buffer_size, 39 communicator_type comm = communicator_type()); 40 41 mpi_process_group(); 42 mpi_process_group(const mpi_process_group&, boost::parallel::attach_distributed_object); 43 44 // Triggers 45 template<typename Type, typename Handler> 46 void trigger(int tag, const Handler& handler); 47 48 template<typename Type, typename Handler> 49 void trigger_with_reply(int tag, const Handler& handler); 50 51 trigger_receive_context trigger_context() const; 52 53 // Helper operations 54 void poll(); 55 mpi_process_group base() const; 56 }; 57 58 // Process query 59 int process_id(const mpi_process_group&); 60 int num_processes(const mpi_process_group&); 61 62 // Message transmission 63 template<typename T> 64 void send(const mpi_process_group& pg, int dest, int tag, const T& value); 65 66 template<typename T> 67 void receive(const mpi_process_group& pg, int source, int tag, T& value); 68 69 optional<std::pair<int, int> > probe(const mpi_process_group& pg); 70 71 // Synchronization 72 void synchronize(const mpi_process_group& pg); 73 74 // Out-of-band communication 75 template<typename T> 76 void send_oob(const mpi_process_group& pg, int dest, int tag, const T& value); 77 78 template<typename T, typename U> 79 void 80 send_oob_with_reply(const mpi_process_group& pg, int dest, int 81 tag, const T& send_value, U& receive_value); 82 83 template<typename T> 84 void receive_oob(const mpi_process_group& pg, int source, int tag, T& value); 85 86 } } } 87 88Since the ``mpi_process_group`` is an implementation of the `process 89group`_ interface, we omit the description of most of the functions in 90the prototype. Two constructors need special mentioning: 91 92:: 93 94 mpi_process_group(communicator_type comm = communicator_type()); 95 96The constructor can take an optional MPI communicator. As default a communicator 97constructed from MPI_COMM_WORLD is used. 98 99:: 100 101 mpi_process_group(std::size_t num_headers, std::size_t buffer_size, 102 communicator_type comm = communicator_type()); 103 104 105For performance fine tuning the maximum number of headers in a message batch 106(num_headers) and the maximum combined size of batched messages (buffer_size) 107can be specified. The maximum message size of a batch is 10816*num_headers+buffer_size. Sensible default values have been found by optimizing 109a typical application on a cluster with Ethernet network, and are num_header=64k 110and buffer_size=1MB, for a total maximum batches message size of 2MB. 111 112 113 114----------------------------------------------------------------------------- 115 116Copyright (C) 2007 Douglas Gregor 117 118Copyright (C) 2007 Matthias Troyer 119 120.. |Logo| image:: pbgl-logo.png 121 :align: middle 122 :alt: Parallel BGL 123 :target: http://www.osl.iu.edu/research/pbgl 124 125.. _process group: process_group.html 126
