MPI BSP Process GroupContents
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