As stated before, if you are passing durations in telemetry measurements, you use System.monotonic_time to capture the starting point and ending point and take the difference between the two. This is now a duration in “native” units. Which will be unique to your system. The convention is to use native units unless specified otherwise as described here: Telemetry Conventions.
You can convert the duration into a different unit of time like so: System.convert_time_unit(duration, :native, :millisecond).
