Joseph K. Myers

Monday, May 26, 2003

Timings

Timings should be reported [correction, 2004/01/15] in terms of a frequency, that is, a time per unit. Presently this is generally in s/MB.

The amount of timed operation must be at least 100 times the number of reported units. If units are given in s/MB, for example, then at least 100 MB of flow must have been timed to evaluate the frequency. Simply recording than one MB took 0.89 seconds is insufficient to state that the rate is 0.89 s/MB.

Of course, the frequency may be stated as a rate, i.e., a unit per time, by inverting the fraction. However, it should not be changed so that the time is an integer: 1 MB/0.89s is acceptable; 1.12 MB/s is not. The second value is not illegal to report, but the first is the actual timing result.

http://www.myersdaily.org/joseph/unix/timings.txt