mirror of https://github.com/QMCPACK/qmcpack.git
50 lines
1.7 KiB
C++
50 lines
1.7 KiB
C++
#if COMPILATION_INSTRUCTIONS
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mpicxx -O3 -std=c++14 -Wall `#-Wfatal-errors` $0 -o $0x.x -lboost_serialization && time mpirun -np 4 $0x.x $@ && rm -f $0x.x; exit
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#endif
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#include "alf/boost/mpi3/main.hpp"
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#include "alf/boost/mpi3/communicator.hpp"
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#include "alf/boost/mpi3/process.hpp"
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#include <random>
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namespace mpi3 = boost::mpi3;
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using std::cout;
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std::random_device rd;
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std::mt19937 gen(rd());
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std::uniform_real_distribution<> dis;
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int mpi3::main(int, char*[], mpi3::communicator& world){
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int elements_per_proc = 5000;
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std::vector<double> v;
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if(world.rank() == 0){
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v.resize(elements_per_proc*world.size(), -1.);
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std::generate(v.begin(), v.end(), [&](){return dis(gen);});
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cout << "serial average " << std::accumulate(v.begin(), v.end(), 0.)/v.size() << '\n';
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}
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std::vector<double> partial_v(elements_per_proc, -1.);
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world.scatter_from(partial_v.begin(), partial_v.end(), v.begin(), 0);
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double partial_ave = std::accumulate(partial_v.begin(), partial_v.end(), 0.)/partial_v.size();
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{
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std::vector<double> partial_aves = world.gather_value(partial_ave, 0); // std::vector<double> subaves = (world[0] += subave);
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if(world.rank() == 0){
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assert(partial_aves.size() == (unsigned)world.size());
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cout << "parallel average: " << std::accumulate(partial_aves.begin(), partial_aves.end(), 0.)/partial_aves.size() << '\n';
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}else{
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assert(partial_aves.empty());
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}
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}
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{
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// std::vector<double> partial_aves = world.all_gather_value(partial_ave);
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std::vector<double> partial_aves = (world |= partial_ave);
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assert(partial_aves.size() == (unsigned)world.size());
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cout << "parallel average on " << world.rank() << ": " << std::accumulate(partial_aves.begin(), partial_aves.end(), 0.)/partial_aves.size() << std::endl;
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}
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return 0;
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}
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