source: doc/theses/thierry_delisle_PhD/code/readyQ_proto/bts.cpp @ 433e2c3

#include <array>
#include <iomanip>
#include <iostream>
#include <locale>
#include <string>
#include <thread>
#include <vector>

#include <getopt.h>
#include <unistd.h>
#include <sys/sysinfo.h>

#include "utils.hpp"

// ================================================================================================
//                        UTILS
// ================================================================================================

struct local_stat_t {
        size_t cnt = 0;
};

struct global_stat_t {
        std::atomic_size_t cnt = { 0 };
};

void atomic_max(std::atomic_size_t & target, size_t value) {
        for(;;) {
                size_t expect = target.load(std::memory_order_relaxed);
                if(value <= expect) return;
                bool success = target.compare_exchange_strong(expect, value);
                if(success) return;
        }
}

void atomic_min(std::atomic_size_t & target, size_t value) {
        for(;;) {
                size_t expect = target.load(std::memory_order_relaxed);
                if(value >= expect) return;
                bool success = target.compare_exchange_strong(expect, value);
                if(success) return;
        }
}

void tally_stats(global_stat_t & global, local_stat_t & local) {
        global.cnt   += local.cnt;
}

void waitfor(double & duration, barrier_t & barrier, std::atomic_bool & done) {
        std::cout << "Starting" << std::endl;
        auto before = Clock::now();
        barrier.wait(0);

        while(true) {
                usleep(100000);
                auto now = Clock::now();
                duration_t durr = now - before;
                if( durr.count() > duration ) {
                        done = true;
                        break;
                }
                std::cout << "\r" << std::setprecision(4) << durr.count();
                std::cout.flush();
        }

        barrier.wait(0);
        auto after = Clock::now();
        duration_t durr = after - before;
        duration = durr.count();
        std::cout << "\rClosing down" << std::endl;
}

void waitfor(double & duration, barrier_t & barrier, const std::atomic_size_t & count) {
        std::cout << "Starting" << std::endl;
        auto before = Clock::now();
        barrier.wait(0);

        while(true) {
                usleep(100000);
                size_t c = count.load();
                if( c == 0 ) {
                        break;
                }
                std::cout << "\r" << c;
                std::cout.flush();
        }

        barrier.wait(0);
        auto after = Clock::now();
        duration_t durr = after - before;
        duration = durr.count();
        std::cout << "\rClosing down" << std::endl;
}

void print_stats(double duration, unsigned nthread, global_stat_t & global) {
        std::cout << "Done" << std::endl;

        size_t ops = global.cnt;
        size_t ops_sec = size_t(double(ops) / duration);
        size_t ops_thread = ops_sec / nthread;
        auto dur_nano = duration_cast<std::nano>(1.0);

        std::cout << "Duration      : " << duration << "s\n";
        std::cout << "ns/Op         : " << ( dur_nano / ops_thread )<< "\n";
        std::cout << "Ops/sec/thread: " << ops_thread << "\n";
        std::cout << "Ops/sec       : " << ops_sec << "\n";
        std::cout << "Total ops     : " << ops << "\n";
}

static inline bool bts(std::atomic_size_t & target, size_t bit ) {
        /*
        int result = 0;
        asm volatile(
                "LOCK btsq %[bit], %[target]\n\t"
                :"=@ccc" (result)
                : [target] "m" (target), [bit] "r" (bit)
        );
        return result != 0;
        /*/
        size_t mask = 1ul << bit;
        size_t ret = target.fetch_or(mask, std::memory_order_relaxed);
        return (ret & mask) != 0;
        //*/
}

static inline bool btr(std::atomic_size_t & target, size_t bit ) {
        /*
        int result = 0;
        asm volatile(
                "LOCK btrq %[bit], %[target]\n\t"
                :"=@ccc" (result)
                : [target] "m" (target), [bit] "r" (bit)
        );
        return result != 0;
        /*/
        size_t mask = 1ul << bit;
        size_t ret = target.fetch_and(~mask, std::memory_order_relaxed);
        return (ret & mask) != 0;
        //*/
}

// ================================================================================================
//                        EXPERIMENTS
// ================================================================================================

// ================================================================================================
__attribute__((noinline)) void runPingPong_body(
        std::atomic<bool>& done,
        local_stat_t & local,
        std::atomic_size_t & target,
        size_t id
) {
        while(__builtin_expect(!done.load(std::memory_order_relaxed), true)) {

                bool ret;
                ret = bts(target, id);
                assert(!ret);

                // -----

                ret = btr(target, id);
                assert(ret);
                local.cnt++;
        }
}

void run(unsigned nthread, double duration) {
        // Barrier for synchronization
        barrier_t barrier(nthread + 1);

        // Data to check everything is OK
        global_stat_t global;

        // Flag to signal termination
        std::atomic_bool done  = { false };

        std::cout << "Initializing ";
        // List being tested
        std::atomic_size_t word = { 0 };
        {
                std::thread * threads[nthread];
                unsigned i = 1;
                for(auto & t : threads) {
                        t = new std::thread([&done, &word, &barrier, &global](unsigned tid) {
                                local_stat_t local;

                                // affinity(tid);

                                barrier.wait(tid);

                                // EXPERIMENT START

                                runPingPong_body(done, local, word, tid - 1);

                                // EXPERIMENT END

                                barrier.wait(tid);

                                tally_stats(global, local);
                        }, i++);
                }

                waitfor(duration, barrier, done);

                for(auto t : threads) {
                        t->join();
                        delete t;
                }
        }

        print_stats(duration, nthread, global);
}

// ================================================================================================

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

        double duration   = 5.0;
        unsigned nthreads = 2;

        std::cout.imbue(std::locale(""));

        for(;;) {
                static struct option options[] = {
                        {"duration",  required_argument, 0, 'd'},
                        {"nthreads",  required_argument, 0, 't'},
                        {0, 0, 0, 0}
                };

                int idx = 0;
                int opt = getopt_long(argc, argv, "d:t:", options, &idx);

                std::string arg = optarg ? optarg : "";
                size_t len = 0;
                switch(opt) {
                        case -1:
                                if(optind != argc) {
                                        std::cerr << "Too many arguments " << argc << " " << idx << std::endl;
                                        goto usage;
                                }
                                goto run;
                        // Numeric Arguments
                        case 'd':
                                try {
                                        duration = std::stod(optarg, &len);
                                        if(len != arg.size()) { throw std::invalid_argument(""); }
                                } catch(std::invalid_argument &) {
                                        std::cerr << "Duration must be a valid double, was " << arg << std::endl;
                                        goto usage;
                                }
                                break;
                        case 't':
                                try {
                                        nthreads = std::stoul(optarg, &len);
                                        if(len != arg.size() || nthreads > (8 * sizeof(size_t))) { throw std::invalid_argument(""); }
                                } catch(std::invalid_argument &) {
                                        std::cerr << "Number of threads must be a positive integer less than or equal to " << sizeof(size_t) * 8 << ", was " << arg << std::endl;
                                        goto usage;
                                }
                                break;
                        // Other cases
                        default: /* ? */
                                std::cerr << opt << std::endl;
                        usage:
                                std::cerr << "Usage: " << argv[0] << ": [options]" << std::endl;
                                std::cerr << std::endl;
                                std::cerr << "  -d, --duration=DURATION  Duration of the experiment, in seconds" << std::endl;
                                std::cerr << "  -t, --nthreads=NTHREADS  Number of kernel threads" << std::endl;
                                std::exit(1);
                }
        }
        run:

        check_cache_line_size();

        std::cout << "Running " << nthreads << " threads for " << duration << " seconds" << std::endl;
        run(nthreads, duration);
        return 0;
}