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#include <iostream>
#include <iomanip>
#include <fstream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <cmath>
#include <boost/scope_exit.hpp>
#include <boost/program_options.hpp>
#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>
#include <amgcl/mpi/direct_solver/runtime.hpp>
#include <amgcl/profiler.hpp>
namespace amgcl {
profiler<> prof;
}
int main(int argc, char *argv[]) {
int provided;
MPI_Init_thread(&argc, &argv, MPI_THREAD_MULTIPLE, &provided);
BOOST_SCOPE_EXIT(void) {
MPI_Finalize();
} BOOST_SCOPE_EXIT_END
amgcl::mpi::communicator comm(MPI_COMM_WORLD);
if (comm.rank == 0)
std::cout << "World size: " << comm.size << std::endl;
namespace po = boost::program_options;
po::options_description desc("Options");
desc.add_options()
("help,h", "show help")
(
"size,n",
po::value<int>()->default_value(128),
"domain size"
)
("prm-file,P",
po::value<std::string>(),
"Parameter file in json format. "
)
(
"prm,p",
po::value< std::vector<std::string> >()->multitoken(),
"Parameters specified as name=value pairs. "
"May be provided multiple times. Examples:\n"
" -p solver.tol=1e-3\n"
" -p precond.coarse_enough=300"
)
;
po::variables_map vm;
po::store(po::parse_command_line(argc, argv, desc), vm);
po::notify(vm);
if (vm.count("help")) {
if (comm.rank == 0) std::cout << desc << std::endl;
return 0;
}
boost::property_tree::ptree prm;
if (vm.count("prm-file")) {
read_json(vm["prm-file"].as<std::string>(), prm);
}
if (vm.count("prm")) {
for(const std::string &v : vm["prm"].as<std::vector<std::string> >()) {
amgcl::put(prm, v);
}
}
const int n = vm["size"].as<int>();
const int n2 = n * n;
using amgcl::prof;
int chunk = (n2 + comm.size - 1) / comm.size;
int chunk_start = comm.rank * chunk;
int chunk_end = std::min(chunk_start + chunk, n2);
chunk = chunk_end - chunk_start;
std::vector<int> domain(comm.size + 1);
MPI_Allgather(&chunk, 1, MPI_INT, &domain[1], 1, MPI_INT, comm);
std::partial_sum(domain.begin(), domain.end(), domain.begin());
prof.tic("assemble");
amgcl::backend::crs<double> A;
A.set_size(chunk, domain.back(), true);
A.set_nonzeros(chunk * 5);
std::vector<double> rhs(chunk, 1);
const double h2i = (n - 1) * (n - 1);
for(int idx = chunk_start, row = 0, head = 0; idx < chunk_end; ++idx, ++row) {
int j = idx / n;
int i = idx % n;
if (j > 0) {
A.col[head] = idx - n;
A.val[head] = -h2i;
++head;
}
if (i > 0) {
A.col[head] = idx - 1;
A.val[head] = -h2i;
++head;
}
A.col[head] = idx;
A.val[head] = 4 * h2i;
++head;
if (i + 1 < n) {
A.col[head] = idx + 1;
A.val[head] = -h2i;
++head;
}
if (j + 1 < n) {
A.col[head] = idx + n;
A.val[head] = -h2i;
++head;
}
A.ptr[row + 1] = head;
}
A.nnz = A.ptr[chunk];
prof.toc("assemble");
prof.tic("setup");
amgcl::runtime::mpi::direct::solver<double> solve(comm, A, prm);
prof.toc("setup");
prof.tic("solve");
std::vector<double> x(chunk);
solve(rhs, x);
solve(rhs, x);
prof.toc("solve");
prof.tic("save");
if (comm.rank == 0) {
std::vector<double> X(n2);
std::copy(x.begin(), x.end(), X.begin());
for(int i = 1; i < comm.size; ++i)
MPI_Recv(&X[domain[i]], domain[i+1] - domain[i], MPI_DOUBLE, i, 42, comm, MPI_STATUS_IGNORE);
std::ofstream f("out.dat", std::ios::binary);
f.write((char*)&n2, sizeof(int));
f.write((char*)X.data(), n2 * sizeof(double));
} else {
MPI_Send(x.data(), chunk, MPI_DOUBLE, 0, 42, comm);
}
prof.toc("save");
if (comm.rank == 0) {
std::cout << prof << std::endl;
}
}
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