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Contents
The MPI mpi_process_group is an implementation of the process group interface using the Message Passing Interface (MPI). It is the primary process group used in the Parallel BGL at this time.
Header <boost/graph/distributed/mpi_process_group.hpp>
namespace boost { namespace graph { namespace distributed { class mpi_process_group { public: typedef boost::mpi::communicator communicator_type; // Process group constructors mpi_process_group(communicator_type comm = communicator_type()); mpi_process_group(std::size_t num_headers, std::size_t buffer_size, communicator_type comm = communicator_type()); mpi_process_group(); mpi_process_group(const mpi_process_group&, boost::parallel::attach_distributed_object); // Triggers template<typename Type, typename Handler> void trigger(int tag, const Handler& handler); template<typename Type, typename Handler> void trigger_with_reply(int tag, const Handler& handler); trigger_receive_context trigger_context() const; // Helper operations void poll(); mpi_process_group base() const; }; // Process query int process_id(const mpi_process_group&); int num_processes(const mpi_process_group&); // Message transmission template<typename T> void send(const mpi_process_group& pg, int dest, int tag, const T& value); template<typename T> void receive(const mpi_process_group& pg, int source, int tag, T& value); optional<std::pair<int, int> > probe(const mpi_process_group& pg); // Synchronization void synchronize(const mpi_process_group& pg); // Out-of-band communication template<typename T> void send_oob(const mpi_process_group& pg, int dest, int tag, const T& value); template<typename T, typename U> void send_oob_with_reply(const mpi_process_group& pg, int dest, int tag, const T& send_value, U& receive_value); template<typename T> void receive_oob(const mpi_process_group& pg, int source, int tag, T& value); } } }
Since the mpi_process_group is an implementation of the process group interface, we omit the description of most of the functions in the prototype. Two constructors need special mentioning:
mpi_process_group(communicator_type comm = communicator_type());
The constructor can take an optional MPI communicator. As default a communicator constructed from MPI_COMM_WORLD is used.
mpi_process_group(std::size_t num_headers, std::size_t buffer_size, communicator_type comm = communicator_type());
For performance fine tuning the maximum number of headers in a message batch (num_headers) and the maximum combined size of batched messages (buffer_size) can be specified. The maximum message size of a batch is 16*num_headers+buffer_size. Sensible default values have been found by optimizing a typical application on a cluster with Ethernet network, and are num_header=64k and buffer_size=1MB, for a total maximum batches message size of 2MB.
Copyright (C) 2007 Douglas Gregor
Copyright (C) 2007 Matthias Troyer