The papi-logging program

The papi logging example.

This example depends on simple-solver-logging.

Table of contents
Introduction About the example The commented program	Results Comments about programming and debugging The plain program

Introduction

About the example

The commented program

#include <ginkgo/ginkgo.hpp>


#include <papi.h>
#include <fstream>
#include <iostream>
#include <string>
#include <thread>


namespace {


void papi_add_event(const std::string &event_name, int &eventset)
{
    int code;
    int ret_val = PAPI_event_name_to_code(event_name.c_str(), &code);
    if (PAPI_OK != ret_val) {
        std::cerr << "Error at PAPI_name_to_code()" << std::endl;
        std::exit(-1);
    }

    ret_val = PAPI_add_event(eventset, code);
    if (PAPI_OK != ret_val) {
        std::cerr << "Error at PAPI_name_to_code()" << std::endl;
        std::exit(-1);
    }
}


template <typename T>
std::string to_string(T *ptr)
{
    std::ostringstream os;
    os << reinterpret_cast<gko::uintptr>(ptr);
    return os.str();
}


}  // namespace


int init_papi_counters(std::string solver_name, std::string A_name)
{

Initialize PAPI, add events and start it up

    int eventset = PAPI_NULL;
    int ret_val = PAPI_library_init(PAPI_VER_CURRENT);
    if (ret_val != PAPI_VER_CURRENT) {
        std::cerr << "Error at PAPI_library_init()" << std::endl;
        std::exit(-1);
    }
    ret_val = PAPI_create_eventset(&eventset);
    if (PAPI_OK != ret_val) {
        std::cerr << "Error at PAPI_create_eventset()" << std::endl;
        std::exit(-1);
    }

    std::string simple_apply_string("sde:::ginkgo0::linop_apply_completed::");
    std::string advanced_apply_string(
        "sde:::ginkgo0::linop_advanced_apply_completed::");
    papi_add_event(simple_apply_string + solver_name, eventset);
    papi_add_event(simple_apply_string + A_name, eventset);
    papi_add_event(advanced_apply_string + A_name, eventset);

    ret_val = PAPI_start(eventset);
    if (PAPI_OK != ret_val) {
        std::cerr << "Error at PAPI_start()" << std::endl;
        std::exit(-1);
    }
    return eventset;
}


void print_papi_counters(int eventset)
{

Stop PAPI and read the linop_apply_completed event for all of them

long long int values[3];
int ret_val = PAPI_stop(eventset, values);
if (PAPI_OK != ret_val) {
    std::cerr << "Error at PAPI_stop()" << std::endl;
    std::exit(-1);
}

PAPI_shutdown();

Print all values returned from PAPI

    std::cout << "PAPI SDE counters:" << std::endl;
    std::cout << "solver did " << values[0] << " applies." << std::endl;
    std::cout << "A did " << values[1] << " simple applies." << std::endl;
    std::cout << "A did " << values[2] << " advanced applies." << std::endl;
}


int main(int argc, char *argv[])
{

Some shortcuts

using vec = gko::matrix::Dense<>;
using mtx = gko::matrix::Csr<>;
using cg = gko::solver::Cg<>;

Print version information

std::cout << gko::version_info::get() << std::endl;

Figure out where to run the code

std::shared_ptr<gko::Executor> exec;
if (argc == 1 || std::string(argv[1]) == "reference") {
    exec = gko::ReferenceExecutor::create();
} else if (argc == 2 && std::string(argv[1]) == "omp") {
    exec = gko::OmpExecutor::create();
} else if (argc == 2 && std::string(argv[1]) == "cuda" &&
           gko::CudaExecutor::get_num_devices() > 0) {
    exec = gko::CudaExecutor::create(0, gko::OmpExecutor::create());
} else {
    std::cerr << "Usage: " << argv[0] << " [executor]" << std::endl;
    std::exit(-1);
}

Read data

auto A = share(gko::read<mtx>(std::ifstream("data/A.mtx"), exec));
auto b = gko::read<vec>(std::ifstream("data/b.mtx"), exec);
auto x = gko::read<vec>(std::ifstream("data/x0.mtx"), exec);

Generate solver

auto solver_gen =
    cg::build()
        .with_criteria(
            gko::stop::Iteration::build().with_max_iters(20u).on(exec),
            gko::stop::ResidualNormReduction<>::build()
                .with_reduction_factor(1e-20)
                .on(exec))
        .on(exec);
auto solver = solver_gen->generate(A);

In this example, we split as much as possible the Ginkgo solver/logger and the PAPI interface. Note that the PAPI ginkgo namespaces are of the form sde:::ginkgo<x> where <x> starts from 0 and is incremented with every new PAPI logger.

int eventset =
    init_papi_counters(to_string(solver.get()), to_string(A.get()));

Create a PAPI logger and add it to relevant LinOps

auto logger = gko::log::Papi<>::create(
    exec, gko::log::Logger::linop_apply_completed_mask |
              gko::log::Logger::linop_advanced_apply_completed_mask);
solver->add_logger(logger);
A->add_logger(logger);

Solve system

solver->apply(lend(b), lend(x));

Stop PAPI event gathering and print the counters

print_papi_counters(eventset);

Print solution

std::cout << "Solution (x): \n";
write(std::cout, lend(x));

Calculate residual

    auto one = gko::initialize<vec>({1.0}, exec);
    auto neg_one = gko::initialize<vec>({-1.0}, exec);
    auto res = gko::initialize<vec>({0.0}, exec);
    A->apply(lend(one), lend(x), lend(neg_one), lend(b));
    b->compute_norm2(lend(res));

    std::cout << "Residual norm sqrt(r^T r): \n";
    write(std::cout, lend(res));
}

Results

The following is the expected result:

PAPI SDE counters:
solver did 1 applies.
A did 20 simple applies.
A did 1 advanced applies.
Solution (x):
%%MatrixMarket matrix array real general
19 1
0.252218
0.108645
0.0662811
0.0630433
0.0384088
0.0396536
0.0402648
0.0338935
0.0193098
0.0234653
0.0211499
0.0196413
0.0199151
0.0181674
0.0162722
0.0150714
0.0107016
0.0121141
0.0123025
Residual norm sqrt(r^T r):
%%MatrixMarket matrix array real general
1 1
8.87107e-16

Comments about programming and debugging

The plain program

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#include <ginkgo/ginkgo.hpp>


#include <papi.h>
#include <fstream>
#include <iostream>
#include <string>
#include <thread>


namespace {


void papi_add_event(const std::string &event_name, int &eventset)
{
    int code;
    int ret_val = PAPI_event_name_to_code(event_name.c_str(), &code);
    if (PAPI_OK != ret_val) {
        std::cerr << "Error at PAPI_name_to_code()" << std::endl;
        std::exit(-1);
    }

    ret_val = PAPI_add_event(eventset, code);
    if (PAPI_OK != ret_val) {
        std::cerr << "Error at PAPI_name_to_code()" << std::endl;
        std::exit(-1);
    }
}


template <typename T>
std::string to_string(T *ptr)
{
    std::ostringstream os;
    os << reinterpret_cast<gko::uintptr>(ptr);
    return os.str();
}


}  // namespace


int init_papi_counters(std::string solver_name, std::string A_name)
{
    int eventset = PAPI_NULL;
    int ret_val = PAPI_library_init(PAPI_VER_CURRENT);
    if (ret_val != PAPI_VER_CURRENT) {
        std::cerr << "Error at PAPI_library_init()" << std::endl;
        std::exit(-1);
    }
    ret_val = PAPI_create_eventset(&eventset);
    if (PAPI_OK != ret_val) {
        std::cerr << "Error at PAPI_create_eventset()" << std::endl;
        std::exit(-1);
    }

    std::string simple_apply_string("sde:::ginkgo0::linop_apply_completed::");
    std::string advanced_apply_string(
        "sde:::ginkgo0::linop_advanced_apply_completed::");
    papi_add_event(simple_apply_string + solver_name, eventset);
    papi_add_event(simple_apply_string + A_name, eventset);
    papi_add_event(advanced_apply_string + A_name, eventset);

    ret_val = PAPI_start(eventset);
    if (PAPI_OK != ret_val) {
        std::cerr << "Error at PAPI_start()" << std::endl;
        std::exit(-1);
    }
    return eventset;
}


void print_papi_counters(int eventset)
{
    long long int values[3];
    int ret_val = PAPI_stop(eventset, values);
    if (PAPI_OK != ret_val) {
        std::cerr << "Error at PAPI_stop()" << std::endl;
        std::exit(-1);
    }

    PAPI_shutdown();

    std::cout << "PAPI SDE counters:" << std::endl;
    std::cout << "solver did " << values[0] << " applies." << std::endl;
    std::cout << "A did " << values[1] << " simple applies." << std::endl;
    std::cout << "A did " << values[2] << " advanced applies." << std::endl;
}


int main(int argc, char *argv[])
{
    using vec = gko::matrix::Dense<>;
    using mtx = gko::matrix::Csr<>;
    using cg = gko::solver::Cg<>;

    std::cout << gko::version_info::get() << std::endl;

    std::shared_ptr<gko::Executor> exec;
    if (argc == 1 || std::string(argv[1]) == "reference") {
        exec = gko::ReferenceExecutor::create();
    } else if (argc == 2 && std::string(argv[1]) == "omp") {
        exec = gko::OmpExecutor::create();
    } else if (argc == 2 && std::string(argv[1]) == "cuda" &&
               gko::CudaExecutor::get_num_devices() > 0) {
        exec = gko::CudaExecutor::create(0, gko::OmpExecutor::create());
    } else {
        std::cerr << "Usage: " << argv[0] << " [executor]" << std::endl;
        std::exit(-1);
    }

    auto A = share(gko::read<mtx>(std::ifstream("data/A.mtx"), exec));
    auto b = gko::read<vec>(std::ifstream("data/b.mtx"), exec);
    auto x = gko::read<vec>(std::ifstream("data/x0.mtx"), exec);

    auto solver_gen =
        cg::build()
            .with_criteria(
                gko::stop::Iteration::build().with_max_iters(20u).on(exec),
                gko::stop::ResidualNormReduction<>::build()
                    .with_reduction_factor(1e-20)
                    .on(exec))
            .on(exec);
    auto solver = solver_gen->generate(A);

    int eventset =
        init_papi_counters(to_string(solver.get()), to_string(A.get()));


    auto logger = gko::log::Papi<>::create(
        exec, gko::log::Logger::linop_apply_completed_mask |
                  gko::log::Logger::linop_advanced_apply_completed_mask);
    solver->add_logger(logger);
    A->add_logger(logger);

    solver->apply(lend(b), lend(x));


    print_papi_counters(eventset);

    std::cout << "Solution (x): \n";
    write(std::cout, lend(x));

    auto one = gko::initialize<vec>({1.0}, exec);
    auto neg_one = gko::initialize<vec>({-1.0}, exec);
    auto res = gko::initialize<vec>({0.0}, exec);
    A->apply(lend(one), lend(x), lend(neg_one), lend(b));
    b->compute_norm2(lend(res));

    std::cout << "Residual norm sqrt(r^T r): \n";
    write(std::cout, lend(res));
}