Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!wuarchive!udel!mmdf
From: KPURCELL@liverpool.ac.uk (Kevin Purcell)
Newsgroups: comp.os.minix
Subject: Re: 386 dx vs. sx
Message-ID: <38578@nigel.ee.udel.edu>
Date: 9 Dec 90 17:50:00 GMT
Sender: mmdf@ee.udel.edu
Lines: 47

On Sat, 8 Dec 90 21:36:31 GMT Kenneth J. Hendrickson (kjh@EDU.USC.POLLUX) said:

>In article <18330@hydra.gatech.EDU> ken@dali.gatech.edu (Ken Seefried iii)
> writes:

[clarification of original question]
>Hence my question:  Does Minix 386 use 32-bit integers?  If they do,
>then getting a 386dx will be a big win for Minix 386.
>
>--
>favourite oxymorons:   student athlete, military justice, mercy killing
>Ken Hendrickson N8DGN/6       kjh@usc.edu      ...!uunet!usc!pollux!kjh

I would like to extend this question a little further and in a slightly
different direction. BTW, this question was recently discused in
alt.folklore.computer (!) and comp.sys.unix.wizards.

One thing which does limit 'real' unicies on 386 'IBM-PC' machines is
the I/O, mostly to disk. This is most true when you run them as multi-user
systems. Although their raw processing power is much bigger than, say,
a PDP 11/70 or even a VAX 780, their I/O bandwidth is appallingly bad. They
were designed to run MSDOS as a single user systems and this shows when you
try to run anything a bit more demanding.

So from this point of view, is the how does the difference in bus bandwidth
of a dx compared to an sx affect the overall performance of a multi-user
system. (Minix neophyte question -- does Minix swap in the 386 versions?)

And a second question -- how does a cache on a 386dx affect the performance
of Minix relative to a uncached 386dx. I have heard it said that (again
with a real Unix system on a 386) a 20MHz cached 386dx will easily beat an
uncached 25MHz 386dx.

Finally, what affect is the hard disk system (disk + controller + driver)
performance have on Minix. Are you better buying a better disk and controller
and settling for a 386sx?

All of these questions should be answered for the two cases that most people
encounter -- the single-user case and the multi-user case.

Thanks for listening,
Kevin
                                                      _   .
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