// https://gist.github.com/teknoraver/ebee75c5bc4eb8533b8e761d0e57b7d9
// ctx_clock Copyright (C) 2018 Matteo Croce <mcroce@redhat.com>
// a tool measure the context switch time in clock cycles

#include <algorithm>
#include <iomanip>
#include <iostream>
#include <limits>
#include <unistd.h>
#include <x86intrin.h>

int main()
{
    const size_t N = 1'000'000, W = 6;

    size_t cycles[N];
    unsigned junk;

    for (auto &cycle: cycles)
    {
        auto start = __rdtscp(&junk);
        syscall(-1L);
        auto stop = __rdtscp(&junk);
        cycle = stop - start;
    }

    std::nth_element(cycles, cycles + N / 2, cycles + N);
    std::cout << "context switch clock cycles...\n"
              << "\tminimum: " << std::setw(W)
              << *std::min_element(cycles, cycles + N) << '\n'
              << "\tmedian : " << std::setw(W) << cycles[N / 2] << '\n'
              << "\tmaximun: " << std::setw(W)
              << *std::max_element(cycles, cycles + N) << '\n';
}