Why Overhead Calculation in the latency test?

[dasisttao]

In the latency test, there's an overhead calculation in Publisher. However I can't figure out what for it is. Can someone help?
LatencyTestPublisher.cpp line 396

/* Calculate Overhead */
    start_time_ = std::chrono::steady_clock::now();
    for (int i = 0; i < 1000; ++i)
    {
        end_time_ = std::chrono::steady_clock::now();
    }
    overhead_time_ = std::chrono::duration<double, std::micro>(end_time_ - start_time_) / 1001;
    std::cout << "Overhead " << overhead_time_.count() << " ns" << std::endl;

[EduPonz]

Hi @dasisttao,

It is simply to estimate the time it takes to access the system clock.

[dasisttao]

Got it. Thank you!