dinapoli@rodan.acs.syr.edu (Ron DiNapoli) (03/30/91)
OK Mac system software gurus, here's one for you... A few weeks ago a user of our Prolog system in Germany contacted me. He was wondering why the performance of the system (measures in Logical Inferences Per Second [LIPS] using a standard Prolog program called nrev) on his IIcx was coming in at 17,000 LIPS whereas the published performance figure for that machine is 37,000 LIPS. I couldn't imagine our Prolog system running as slow as he had reported it to be running on a IIcx. To double check I ran the benchmark myself on a IIcx here in Syracuse. The result? An average of around 37,500 LIPS. Just as advertised. My thoughts then turned to the German OS. Perhaps the methods we use to keep track of time don't work the same way under the German OS (Or any other foreign OS)? After pondering over this for a while, I remembered that I had all the International OS files on the latest Developer CD-ROM. I installed the German OS on my Mac II and (Surprise!) the nrev benchmark reported a speed of 13,000 LIPS (The published LIPS figure for a Mac II running ALS Prolog is 30,500 LIPS). I couldn't tell if the system was really running that slow or if the figures were mistakes triggerred by something in the German OS. To test this I put another Mac II next to mine (running the domestic OS) and ran the benchmark on both machines simultaneously. Big Surprise: The Mac II running the domestic OS finished in at least 1/2 the time it took the Mac II running the German OS to finish. The majority of the execution time used by this benchmark is in an abstract machine written entirely in assembly. This machine does not make any toolbox calls and does not perform any I/O. Why would a foreign OS cause this to run at less than 1/2 the speed it does under the domestic OS??? Any explanations??? Ron D. Applied Logic Systems, Inc.