ramamurb@turing.cs.rpi.edu (Badrinath Ramamurthy - Badri) (06/12/90)
Hello everybody, I am attempting to time some of my algorithms on SUN 3 workstations and Sparcstations. In this light I have these questions: 1. What clock (and howmany) does each of these workstations have ? 2. how can I access them ( I am using getrusage and getitimer now )? 3. What are your experiences with the reliability of the timings you get with the methods you use. 4. If you are using some "tricks" to get around inaccuracies in reading the timer(s), please do tell me. -Badri
moss@cs.umass.edu (Eliot Moss) (06/12/90)
While I do not experience with these *particular* machines, I do have experience with VAXStations and DECStations, and suspects Suns and SparcStations are similar. Though the time is stated in units down to microseconds on many machines, the actual update frequency is multiple of milliseconds, generally on interval timer ticks used for time slicing. Typical granularities are 10 to 50 milliseconds. To get accurate timings you usually have to average over *many* events and you have to be careful not to get synchronized with the interval timer ticks. (Sigh; for those of use who like to measure performance, coarse granularity clocks are a real pain!) -- J. Eliot B. Moss, Assistant Professor Department of Computer and Information Science Lederle Graduate Research Center University of Massachusetts Amherst, MA 01003 (413) 545-4206; Moss@cs.umass.edu