Linux 上の C で高精度のタイミングを実現するにはどうすればよいですか?

#include <iostream>
#include <boost/chrono/system_clocks.hpp>

using namespace std;
using namespace boost::chrono;

int main() {
  auto now = system_clock::now();
  nanoseconds ts = duration_cast<nanoseconds>(now - system_clock::from_time_t(0));
  
  cout << "Timestamp: " << ts.count() << " nanoseconds" << endl;
  
  return 0;
}

#include <iostream>
#include <time.h>

using namespace std;

int main() {
  timespec ts;
  
  clock_gettime(CLOCK_MONOTONIC, &ts);
  
  cout << "Timestamp: " << ts.tv_sec << " seconds, "
       << ts.tv_nsec << " nanoseconds" << endl;
  
  return 0;
}