| // Copyright (C) 2005-2006 Douglas Gregor <doug.gregor -at- gmail.com> |
| // Copyright (C) 2004 The Trustees of Indiana University |
| |
| // Use, modification and distribution is subject to the Boost Software |
| // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
| // http://www.boost.org/LICENSE_1_0.txt) |
| |
| // Authors: Douglas Gregor |
| // Andrew Lumsdaine |
| |
| // Message Passing Interface 1.1 -- Section 4.9.1. Reduce |
| #ifndef BOOST_MPI_ALL_REDUCE_HPP |
| #define BOOST_MPI_ALL_REDUCE_HPP |
| |
| // All-reduce falls back to reduce() + broadcast() in some cases. |
| #include <boost/mpi/collectives/broadcast.hpp> |
| #include <boost/mpi/collectives/reduce.hpp> |
| |
| namespace boost { namespace mpi { |
| |
| namespace detail { |
| /********************************************************************** |
| * Simple reduction with MPI_Allreduce * |
| **********************************************************************/ |
| // We are reducing for a type that has an associated MPI |
| // datatype and operation, so we'll use MPI_Allreduce directly. |
| template<typename T, typename Op> |
| void |
| all_reduce_impl(const communicator& comm, const T* in_values, int n, |
| T* out_values, Op /*op*/, mpl::true_ /*is_mpi_op*/, |
| mpl::true_ /*is_mpi_datatype*/) |
| { |
| BOOST_MPI_CHECK_RESULT(MPI_Allreduce, |
| (const_cast<T*>(in_values), out_values, n, |
| boost::mpi::get_mpi_datatype<T>(*in_values), |
| (is_mpi_op<Op, T>::op()), comm)); |
| } |
| |
| /********************************************************************** |
| * User-defined reduction with MPI_Allreduce * |
| **********************************************************************/ |
| // We are reducing at the root for a type that has an associated MPI |
| // datatype but with a custom operation. We'll use MPI_Reduce |
| // directly, but we'll need to create an MPI_Op manually. |
| template<typename T, typename Op> |
| void |
| all_reduce_impl(const communicator& comm, const T* in_values, int n, |
| T* out_values, Op op, mpl::false_ /*is_mpi_op*/, |
| mpl::true_ /*is_mpi_datatype*/) |
| { |
| user_op<Op, T> mpi_op(op); |
| BOOST_MPI_CHECK_RESULT(MPI_Allreduce, |
| (const_cast<T*>(in_values), out_values, n, |
| boost::mpi::get_mpi_datatype<T>(*in_values), |
| mpi_op.get_mpi_op(), comm)); |
| } |
| |
| /********************************************************************** |
| * User-defined, tree-based reduction for non-MPI data types * |
| **********************************************************************/ |
| // We are reducing at the root for a type that has no associated MPI |
| // datatype and operation, so we'll use a simple tree-based |
| // algorithm. |
| template<typename T, typename Op> |
| void |
| all_reduce_impl(const communicator& comm, const T* in_values, int n, |
| T* out_values, Op op, mpl::false_ /*is_mpi_op*/, |
| mpl::false_ /*is_mpi_datatype*/) |
| { |
| reduce(comm, in_values, n, out_values, op, 0); |
| broadcast(comm, out_values, n, 0); |
| } |
| } // end namespace detail |
| |
| template<typename T, typename Op> |
| inline void |
| all_reduce(const communicator& comm, const T* in_values, int n, T* out_values, |
| Op op) |
| { |
| detail::all_reduce_impl(comm, in_values, n, out_values, op, |
| is_mpi_op<Op, T>(), is_mpi_datatype<T>()); |
| } |
| |
| template<typename T, typename Op> |
| inline void |
| all_reduce(const communicator& comm, const T& in_value, T& out_value, Op op) |
| { |
| detail::all_reduce_impl(comm, &in_value, 1, &out_value, op, |
| is_mpi_op<Op, T>(), is_mpi_datatype<T>()); |
| } |
| |
| template<typename T, typename Op> |
| T all_reduce(const communicator& comm, const T& in_value, Op op) |
| { |
| T result; |
| ::boost::mpi::all_reduce(comm, in_value, result, op); |
| return result; |
| } |
| |
| } } // end namespace boost::mpi |
| |
| #endif // BOOST_MPI_ALL_REDUCE_HPP |