How to calculate the module time in C++ OpenCV?

method1: 

         double t = (double)cv::getTickCount();
        bool status = weightedMovingVariance(frame, output, count);
        t = ((double)cv::getTickCount() - t)/cv::getTickFrequency();
        std::cout << "Times passed in seconds: " << t << std::endl;

method2:

cv::TickMeter tm;

tm.start();

// do something ...

tm.stop();

std::cout << "Total time: " << tm.getTimeSec() << std::endl;