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Asri-unix.1178 net.works utzoo!decvax!cca!sri-unix!DPR@MIT-XX Wed Apr 7 07:27:30 1982 Hank Walker and Performance Hank Walker's performance comments touched a nerve. "the only way to compare architectures is in assembly language"? Pish tush. Let Hank write all his programs in assembly language, then. No one except hardware-only bigots has made that mistake for the last 10 years. If a salesman told me that I'd throw him out of my office.

It is true that better and worse compilers exist, and it may be true that the VAX is wonderful when you have a good compiler. Show us.

On the other hand, Pratt in his comments never compares programs that do a lot of I/O. Instruction set architecture has very little effect on the performance of "REAL" programs (i.e. other than Puzzle). How fast you can get data into and out of a machine is much more important. The I/O bandwidth on most 68000 machines is pitiful. The VAX, with its MASSBUS, and UNIBUS and cache memory, is a winner here, and shows the real cost difference between big and little machines (the CPU instruction interpreter is such a minor component of cost...)

Getting to a substantive point, we are just about to hook up a gaggle of 750's to a local net, with the disk in some cases being provided by a shared server across the 10MB net. So I think in a couple of months we will have a data point for Pratt on this subject. I am unaware of any useful comparisons and would be interested in other work.

I expect there to be little perceivable difference in UNIX on a 750 with local RK07 and UNIX on a 750 with remote simulated (admittedly we will be using a faster disk for the remote server). As main memory gets cheaper this is probably the way to go to keep your office quiet and your disks reliable.

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