Compare programs or subroutine

[hkvzjal]

How to show the true wall time instead of cpu_time?

A few years ago, I compared time measurement subroutines in Fortran. I recommend date_and_time or omp_get_wtime (OpenMP’s time measurement function) as time measurement subroutines. For system_clock, the count rate is different depending on the compiler. Especially for PGI (currently nvfortran), the upper limit of measurement time is about 36 minutes when integer(int32) is used for the count. Also, system_clock and cpu_time cannot measure the execution time of a parallelized program. The tabl…

You might find this thread very insightful for a comparison of several methods to measure elapsed time.