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https://gitlab.kitware.com/vtk/vtk-m
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d37c1fee79
Adding a Histogram filter example that uses MPI (instead of DIY) for distributed processing.
125 lines
3.7 KiB
C++
125 lines
3.7 KiB
C++
//============================================================================
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// Copyright (c) Kitware, Inc.
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// All rights reserved.
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// See LICENSE.txt for details.
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// This software is distributed WITHOUT ANY WARRANTY; without even
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// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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// PURPOSE. See the above copyright notice for more information.
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//
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// Copyright 2014 National Technology & Engineering Solutions of Sandia, LLC (NTESS).
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// Copyright 2014 UT-Battelle, LLC.
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// Copyright 2014 Los Alamos National Security.
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//
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// Under the terms of Contract DE-NA0003525 with NTESS,
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// the U.S. Government retains certain rights in this software.
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//
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// Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
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// Laboratory (LANL), the U.S. Government retains certain rights in
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// this software.
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//============================================================================
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/*
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* This example demonstrates how one can write a filter that uses MPI
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* for hybrid-parallelism. The `vtkm::filter::Histogram` is another approach for
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* implementing the same that uses DIY. This example doesn't use DIY, instead
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* uses MPI calls directly.
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*/
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#include "HistogramMPI.h"
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#include <vtkm/cont/ArrayPortalToIterators.h>
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#include <vtkm/cont/DataSetFieldAdd.h>
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#include <vtkm/cont/EnvironmentTracker.h>
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// clang-format off
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VTKM_THIRDPARTY_PRE_INCLUDE
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#include VTKM_DIY(diy/mpi.hpp)
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VTKM_THIRDPARTY_POST_INCLUDE
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// clang-format on
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#include <mpi.h>
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#include <algorithm>
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#include <numeric>
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#include <random>
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#include <utility>
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#include <vector>
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namespace
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{
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template <typename T>
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VTKM_CONT vtkm::cont::ArrayHandle<T> CreateArray(T min, T max, vtkm::Id numVals)
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{
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std::mt19937 gen;
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std::uniform_real_distribution<double> dis(static_cast<double>(min), static_cast<double>(max));
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vtkm::cont::ArrayHandle<T> handle;
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handle.Allocate(numVals);
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std::generate(vtkm::cont::ArrayPortalToIteratorBegin(handle.GetPortalControl()),
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vtkm::cont::ArrayPortalToIteratorEnd(handle.GetPortalControl()),
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[&]() { return static_cast<T>(dis(gen)); });
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return handle;
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}
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}
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int main(int argc, char* argv[])
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{
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// setup MPI environment.
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MPI_Init(&argc, &argv);
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// tell VTK-m the communicator to use.
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vtkm::cont::EnvironmentTracker::SetCommunicator(diy::mpi::communicator(MPI_COMM_WORLD));
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int rank, size;
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MPI_Comm_rank(MPI_COMM_WORLD, &rank);
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MPI_Comm_size(MPI_COMM_WORLD, &size);
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if (argc != 2)
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{
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if (rank == 0)
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{
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std::cout << "Usage: " << std::endl << "$ " << argv[0] << " <num-bins>" << std::endl;
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}
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MPI_Finalize();
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return EXIT_FAILURE;
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}
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const vtkm::Id num_bins = static_cast<vtkm::Id>(std::atoi(argv[1]));
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const vtkm::Id numVals = 1024;
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vtkm::cont::MultiBlock mb;
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vtkm::cont::DataSet ds;
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vtkm::cont::DataSetFieldAdd::AddPointField(ds, "pointvar", CreateArray(-1024, 1024, numVals));
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mb.AddBlock(ds);
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example::HistogramMPI histogram;
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histogram.SetActiveField("pointvar");
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histogram.SetNumberOfBins(std::max<vtkm::Id>(1, num_bins));
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vtkm::cont::MultiBlock result = histogram.Execute(mb);
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vtkm::cont::ArrayHandle<vtkm::Id> bins;
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result.GetBlock(0).GetField("histogram").GetData().CopyTo(bins);
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auto binPortal = bins.GetPortalConstControl();
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if (rank == 0)
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{
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// print histogram.
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std::cout << "Histogram (" << num_bins << ")" << std::endl;
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vtkm::Id count = 0;
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for (vtkm::Id cc = 0; cc < num_bins; ++cc)
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{
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std::cout << " bin[" << cc << "] = " << binPortal.Get(cc) << std::endl;
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count += binPortal.Get(cc);
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}
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if (count != numVals * size)
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{
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std::cout << "ERROR: bins mismatched!" << std::endl;
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MPI_Finalize();
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return EXIT_FAILURE;
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}
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}
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MPI_Finalize();
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return EXIT_SUCCESS;
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}
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