Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site utastro.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!mit-eddie!godot!harvard!seismo!ut-sally!utastro!nather From: nather@utastro.UUCP (Ed Nather) Newsgroups: net.micro,net.micro.pc Subject: Longword benchmark on IBM PC and Vax 11/780 Message-ID: <946@utastro.UUCP> Date: Thu, 20-Dec-84 17:59:11 EST Article-I.D.: utastro.946 Posted: Thu Dec 20 17:59:11 1984 Date-Received: Sat, 22-Dec-84 02:15:06 EST Distribution: net Organization: UTexas Astronomy Dept., Austin, Texas Lines: 42 Xref: watmath net.micro:8957 net.micro.pc:3025 [--+- begone!] The December 1984 issue of Byte magazine lists a benchmark test in C that is computationally intensive using long integer arithmetic. The process involves factoring a very large number by an iterative method. The author, David C. Clark, lists execution times for the program on a Z80 computer with a 4MHz clock, for two different compilers, Aztec C and Eco-C. I compiled and ran the same program on an IBM PC (4.77 MHz clock, 8088 chip) using the DeSmet C compiler and the optimizing CI-C86 compiler. I also ran the same program on a Vax 11/780 running 4.2BSD Unix. Here are the execution times: Compiler Computer Execution time (min:sec.) Aztec Z80 2:06 Eco-C Z80 1:41 CI-C86 IBM-PC 0:22.4 DeSmet C IBM-PC 0:10.1 PCC Vax 11/780 0:00.4 Apparent conclusions: 1. 32-bit machines handle 32 bit integers faster than 16 bit machines, and 16 bit machines handle them faster than 8 bit machines, by about an order of magnitude or better in each case. 2. Some compilers generate faster code than others for the same machine, by perhaps a factor of 2 or so. The "optimizing" compiler is not always the faster. 3. Benchmarks aren't the whole story, but I seriously doubt that anyone could devise one that would reverse the ordering of execution times for the above three computers. 4. As a rough figure of merit (for this type of operation only) we can multiply the time by the cost of the computer. Averaging the times where there are more than one, and taking the approximate cost of the computers involved, I get that the Vax and the IBM PC have about the same figure of merit, while the Z80 system is about 3 times worse. Curious. Anybody want to try it on their Macintosh? Ed Nather Astronomy Dept., U of Texas