time how fast we can write to shared memory

write_shared_memory.cc

#include <fstream>
#include <cstdint>
#include <ctime>
#include <iostream>

#include <boost/interprocess/file_mapping.hpp>
#include <boost/interprocess/mapped_region.hpp>

int main()
{
    /*std::string io_file_path{ "c:\\working\\io.bin" };
    std::ofstream iofile{ io_file_path, std::ios::out | std::ios::binary };
    if (iofile.is_open())
    {
        iofile << '\x00';
        iofile.close();
    }*/

    boost::interprocess::file_mapping fm{ "c:\\working\\io.bin", boost::interprocess::read_write };
    boost::interprocess::mapped_region mr(fm, boost::interprocess::read_write, 0, 1);
    uint8_t& io_value = *reinterpret_cast<uint8_t*>(mr.get_address());


    std::clock_t c_start = std::clock();
    for (int i = 0; i < 1'000'000'000; ++i) {
        io_value++;
    }
    std::clock_t c_end = std::clock();

    auto time_elapsed_ms = 1000.0 * (c_end - c_start) / CLOCKS_PER_SEC;
    std::cout << "CPU time used: " << time_elapsed_ms << " ms\n";
    // on my PC it takes about 800ms to 1000ms to write 10^9 times. about 1GHz  
}