zemon@felix.UUCP (Art Zemon) (04/14/87)
Earlier I posted a couple of Dhrystone benchmark results and failed to compare them to anything. My tone in that article came across as a bit too negative so please let me try again. I ran the Dhrystone benchmark on a couple of Minix machines with the following results. When you read the table, keep these points in mind: 1) This benchmark tests the CPU/compiler combination for a "average" mix of instructions. This mix includes integer arithmetic, branches, etc. 2) There are no floating point operations in the Dhrystone program. (A good thing, since floating point is not implemented in the Minix C compiler.) 3) Like most benchmarks, the numbers which come out of this one are not gospel. You can compare Dhrystones between two different machine/compiler combinations and make some sort of judgement about relative speed, but they do NOT tell the whole story. Read point 4. 4) The Dhrystone does not test any operating system or hardware functions. It is completely CPU bound in user mode -- no system calls, no I/O. So with that said, here are the results I came up with. My Zenith is an XT clone with a V20 chip running at the standard XT clock rate. The V20 seems to run programs about 5% - 10% faster than an 8088 in MY experience. The AT is a "real" AT with no mods at all. DHRYSTONE 1.1 BENCHMARK SUMMARY MANUF MODEL PROC CLOCK NOREG REG OS,COMPILER,NOTES ----- ----- ---- ----- ----- --- ----------------- Zenith 151 NEC V20 4.77 162 Minix, cc IBM PC/AT 80286 8.00 767 Minix, cc DEC VAX-11/750 w/FPA 0.00 831 852 UNIX 4.2BSD, cc IBM PC/AT 80286 9.05 1464 1484 XENIX SCO SVR2.1,cc small, IBM PC/AT 80286 8.00 1729 1796 PC-DOS 3.20,Microsoft 4.0 , IBM PC/XT 8088 4.77 326 347 MS-DOS 2.0,Microsoft 3.01 , If you have read this far, you might as well wade through my personal observations on all these numbers. Thanks to Andy T. for pointing out that the AT compares very favorably to a VAX 750 and starting this monolog off. The XT is pretty darned slow. The Dhrystone runs about half as fast as the old Microsoft C compiler on the same CPU and that was not a very good compiler. On the other hand, I can sit at my Zenith and type "ls" and various other commands and the response feels about the same as the VAX 785 I share with a bunch of other software developers. So although the V20/Minix compiler combination is slow, there is a lot to be said for having the CPU available RIGHT NOW, when I need it, and ALL to my self. But if I had serious number crunching to do, this would not be my system of choice. One option is to compile such a program with a "good" compiler under MS-DOS and then convert the .EXE file to a.out format. Another is simply to do my number crunching under MS-DOS. Or maybe somebody with the compiler source will clean up the emited code.... The AT, on the other hand, is very fast for a single user machine. It runs this benchmark at about 90% the speed of a VAX 750. Definitely a nice machine for a single user. Using it "feels" like you have a 750 to yourself -- until you try to do disk I/O. Here you run into one of the things which the Dhrystone does not test. The 750, while not much faster than the AT for Dhrystone cycles, has a lot of I/O hardware. I suspect that you will get two simultaneous comilations done much more quickly on the 750 than on the AT. But then again, the AT is your personal single user machine. All in all, I'm pretty happy with the performance on my Zenith. It isn't very fast but all I'm doing right now is hacking and I'm not in any hurry to "get it done." (I reserve that attitude for the workday!) If I had an AT I could easily use that for my main computer. -- -- Art Zemon FileNet Corporation Costa Mesa, California ...!hplabs!felix!zemon