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Aucbvax.1728 fa.apollo utzoo!duke!decvax!ucbvax!Rick.Rashid@CMU-10A Sun Jun 14 09:10:12 1981 Execution speed of various machines I have noticed a great deal of "rumor" and "gossip" about the relative speed of various machines. In order to reduce the noise factor in these discussions, I decided to run a benchmark program on three different time-sharing systems familiar to most of the correspondents and on the Three Rivers Corp. Perq in my office. The benchmark program used was developed several months ago by Forest Basket of Stanford (and PARC) and is available for inspection on my account on CMUA as "puzzle.pas[p100rr60]". Basically, it has a lot of looping, integer arithmetic, and array access. The program is written in PASCAL and the same program text was used on each of the machines. (Forest originally used this benchmark in various programming languages and has written a paper describing the execution times of the benchmark algorithm on a number of machines in many different languages.)

The systems used in the study were: DEC KL-10/TOPS-10, DEC KA-10/TOPS-10, DEC VAX 11/780 running Berkeley VMUNIX, and PERQ. All benchmarks were run between 10:00 am and 10:30 am Sunday June 14,1981. At the time of execution on the VAX, KA-10 and PERQ only one user (myself) was logged on and active. Several users were logged on the KL-10, but the load was very light (> 50% idle). I measured both CPU time, elapsed real time, and the real time required to compile, link and load the pascal program. Execution times both with and without runtime range checking were obtained. In addition, on the VAX I ran the benchmark with two different PASCAL compilers - the PASCAL compiler supplied by UC Berkeley, and the CMU PERQ/VAX PASCAL compiler (which generates code both for the PERQ and the VAX). The code for the VAX was run through the C code optimizer before execution. Timings were done with <CNTRL-T> for the KL-10 and KA-10, with the UNIX time command on the VAX and with my Casio alarm chronograph on the PERQ. Each benchmark was repeated three times and the times were consistent. All times are in seconds.

Machine Compiler Runtime w/range Runtime w/o range KA-10 PASCAL-10 48.6 39.4 PERQ PERQ/PASCAL 28.6 (elapsed) 22. (elapsed) VAX CMU PASCAL 17.3 10.7 VAX UCB PASCAL 77. 15.8 KL-10 PASCAL-10 9.2 7.3

Machine Compiler Elapsed time w/o range KA-10 PASCAL-10 44 (Single user) PERQ PERQ/PASCAL 22 (Single user) VAX CMU PASCAL 12 (Single user) VAX UCB PASCAL 17 (Single user) KL-10 PASCAL-10 31 (Several users)

Machine Compiler Compile/link/load time (elapsed) KA-10 PASCAL-10 23 (Single user) PERQ PERQ/PASCAL 23 (Single user) VAX CMU PASCAL 32 (Single user) VAX UCB PASCAL 35 (Single user) KL-10 PASCAL-10 23 (Several users)

While I tried to reduce the variables in the test by sticking with the same language (and in the case of the PERQ and VAX the same basic compiler), the comparison of CMU PASCAL and UCB PASCAL on the VAX should be warn the wary that benchmarks test many things besides raw execution speed. They test the compiler and the code it generates, the match-up of machine architecture to language requirements, and the microcode implementation of the machine architecture. As an example, the PERQ/PASCAL compiler both generates fairly bad code and is hampered by the the lack of looping byte codes (the PERQ Q-Code is very similar to UCSD P-Code). My guess is that a factor of two speed-up could be obtained with a good optimizer and a better byte code set.

-Rick

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