thread_local std::default_random_engine gen(0);

std::normal_distribution<float> d{0.0f, 1.0f};

std::ostringstream oss;

oss << "|----> generating " << N << "x" << N << " matrix by thread "

<< std::this_thread::get_id() << "\n";

std::cout << oss.str();

matrix_t mat(N);

for(auto& r : mat) {

r.resize(N);

for(auto& c : r) {

c = d(gen);

}

}

return mat;

std::cout << "========== baseline ==========\n";

auto tbeg = std::chrono::steady_clock::now();

std::cout << "Generating matrix As ...\n";

std::vector<matrix_t> As(D.size());

for(size_t j=0; j<D.size(); ++j) {

As[j] = random_matrix(D[j]);

}

std::cout << "Generating matrix Bs ...\n";

std::vector<matrix_t> Bs(D.size());

for(size_t j=0; j<D.size(); ++j) {

Bs[j] = random_matrix(D[j]);

}

std::cout << "Computing matrix product values Cs ...\n";

std::vector<matrix_t> Cs(D.size());

for(size_t j=0; j<D.size(); ++j) {

Cs[j] = As[j] * Bs[j];

}

auto tend = std::chrono::steady_clock::now();

std::cout << "Baseline takes "

<< std::chrono::duration_cast<std::chrono::milliseconds>(tend-tbeg).count()

<< " ms\n";

std::cout << "========== OpenMP ==========\n";

auto tbeg = std::chrono::steady_clock::now();

std::cout << "Generating matrix As ...\n";

std::vector<matrix_t> As(D.size());

#pragma omp parallel for

for(int j=0; j<(int)D.size(); ++j) {

As[j] = random_matrix(D[j]);

}

std::cout << "Generating matrix Bs ...\n";

std::vector<matrix_t> Bs(D.size());

#pragma omp parallel for

for(int j=0; j<(int)D.size(); ++j) {

Bs[j] = random_matrix(D[j]);

}

std::cout << "Computing matrix product values Cs ...\n";

std::vector<matrix_t> Cs(D.size());

#pragma omp parallel for

for(int j=0; j<(int)D.size(); ++j) {

Cs[j] = As[j] * Bs[j];

}

auto tend = std::chrono::steady_clock::now();

std::cout << "OpenMP takes "

<< std::chrono::duration_cast<std::chrono::milliseconds>(tend-tbeg).count()

<< " ms\n";

std::cout << "========== CppThread ==========\n";

auto tbeg = std::chrono::steady_clock::now();

tf::Threadpool tpl(std::thread::hardware_concurrency());

std::cout << "Generating matrix As ...\n";

std::vector<matrix_t> As(D.size());

std::vector<std::future<void>> futures;

for(size_t j=0; j<D.size(); ++j) {

futures.push_back(tpl.async([&, j] () { As[j] = random_matrix(D[j]); }));

}

std::cout << "Generating matrix Bs ...\n";

std::vector<matrix_t> Bs(D.size());

for(size_t j=0; j<D.size(); ++j) {

futures.push_back(tpl.async([&, j] () { Bs[j] = random_matrix(D[j]); }));

}

std::cout << "Synchronizing As and Bs ...\n";

for(auto& fu : futures) {

fu.get();

}

futures.clear();

std::cout << "Computing matrix product values Cs ...\n";

std::vector<matrix_t> Cs(D.size());

for(size_t j=0; j<D.size(); ++j) {

futures.push_back(tpl.async([&, j] () { Cs[j] = As[j] * Bs[j]; }));

}

std::cout << "Synchronizing Cs ...\n";

for(auto& fu : futures) {

fu.get();

}

auto tend = std::chrono::steady_clock::now();

std::cout << "CppThread takes "

<< std::chrono::duration_cast<std::chrono::milliseconds>(tend-tbeg).count()

<< " ms\n";

auto tbeg = std::chrono::steady_clock::now();

using builder_t = typename tf::Taskflow::Task;

tf::Taskflow tf;

std::cout << "Generating task As ...\n";

std::vector<matrix_t> As(D.size());

std::vector<builder_t> TaskAs;

for(size_t j=0; j<D.size(); ++j) {

TaskAs.push_back(tf.silent_emplace([&, j] () {

As[j] = random_matrix(D[j]);

}));

}

std::cout << "Generating task Bs ...\n";

std::vector<matrix_t> Bs(D.size());

std::vector<builder_t> TaskBs;

for(size_t j=0; j<D.size(); ++j) {

TaskBs.push_back(tf.silent_emplace([&, j] () {

Bs[j] = random_matrix(D[j]);

}));

}

std::cout << "Generating task Cs ...\n";

std::vector<matrix_t> Cs(D.size());

std::vector<builder_t> TaskCs;

for(size_t j=0; j<D.size(); ++j) {

TaskCs.push_back(tf.silent_emplace([&, j] () {

Cs[j] = As[j] * Bs[j];

}));

}

// Build task dependency

for(size_t j=0; j<D.size(); ++j) {

TaskCs[j].gather({TaskAs[j], TaskBs[j]});

}

tf.wait_for_all();

auto tend = std::chrono::steady_clock::now();

std::cout << "Taskflow takes "

<< std::chrono::duration_cast<std::chrono::milliseconds>(tend-tbeg).count()

<< " ms\n";

if(argc != 3) {

std::cerr << "usage: ./matrix [baseline|openmp|cppthread|taskflow] N\n";

std::exit(EXIT_FAILURE);

}

// Create a unbalanced dimension for vector products.

const auto N = std::stoul(argv[2]);

std::vector<size_t> dimensions(N);

std::default_random_engine engine(0);

std::uniform_int_distribution dis(1, 1000);

std::cout << "matrix sizes = [";

for(size_t i=0; i<dimensions.size(); ++i) {

dimensions[i] = dis(engine);

if(i) std::cout << ' ';

std::cout << dimensions[i];

}

std::cout << "]\n";

// Run methods

if(std::string_view method(argv[1]); method == "baseline") {

baseline(dimensions);

}

else if(method == "openmp") {

openmp(dimensions);

}

else if(method == "cppthread") {

cppthread(dimensions);

}

else if(method == "taskflow") {

taskflow(dimensions);

}

else {

std::cerr << "wrong method, shoud be [baseline|openmp|cppthread|taskflow]\n";

}

return 0;