Does anyone have 386SX Unix benchmarks?

[Michael Borza]

In article <BOBM.89Dec18222655 at acsdev.uucp> bobm at acsdev.uucp (Bob Marrow) writes:
>I'm thinking of putting together a Unix system around one
>of the new cheap 386SX boards.  Does anyone have actual
>measurements of the speed of these boards running 32-bit
>protected mode software, as compared with the 386DX?

Noooooo.... don't do it!!  Spend the extra couple'a'hundred bucks for a
real 386.

I thought about doing the same thing, so I borrowed a 386SX with 387SX
from my hardware vendor and tried out ISC 386/ix 2.0.1 dev. system
with X Windows on it and compared it against my 386 systems.  The
386SX had 2 MB of memory on the mother board and 2 MB on a 16-bit
expansion slot board, and had a WD-1003 controller running a 28 ms
ST-506 disk.  I compared it against two 32-bit 386 systems: the first
a 25 MHz 386 with 387, 10 MB of 32-bit memory, and ESDI disk running
ISC 386/ix 2.0.1; the second is a 20 MHz 386 with 387, 4 MB of 32-bit
memory, and ESDI disk running 386/ix 1.0.6.

You can logically argue that this comparison are unfair, given the
differences in disk subsystems and memory architecture; however, the test
was valid for me, since I was trying to decide whether I could live with
the performance of the SX, compared to the machines I use every day at
work.

The results below are for two tests: the first is a make of `flex', which
I consider representative of the kinds of software engineering stuff I do.
The second was for a small floating point test (lots of exps, ln's,...).
Times are given in minutes:seconds, rounded to the nearest second.

      16 MHz 386SX             25 MHz 386          20 MHz 386
      ISC 2.0.1                ISC 2.0.1           ISC 1.0.6

real  11:37                     1:56                2:25
user  10:07                     1:20                1:18
sys    0:37                     0:11                0:13

real   0:50                     0:08                0:15
user   0:43                     0:07                0:08
sys    0:02                     0:00                0:01


Just based on memory bus bandwidth and clock speed considerations we
expect the SX to be 3.125 times slower than the 25 MHz 386, and 2.5
times slower than the 20 MHz 386.  If you multiply out the sys times
quoted above, you'll get roughly these ratios.  The difference in the
remaining times is due to disk performance and the effects of the
expansion bus memory card.

Subjectively, the system felt about the same speed as my old 10 MHz AT
running Microport SV/AT UNIX.  X-Windows performance was terrible.  I
originally tried it out without a 387SX, but watching the screen repaint
was like watching paint dry.  With the 387SX, performance was much better,
but in the long run, it would have slowly driven my nuts to keep using
this turkey.  I strongly suggest you try to borrow one of these to try
out before you buy.  For me, the performance hit just wasn't worth the
paltry savings.

mike borza.
-- 
Michael Borza              Antel Optronics Inc.
(416)335-5507              3325B Mainway, Burlington, Ont., Canada  L7M 1A6
work: mike at antel.UUCP  or  uunet!utai!utgpu!maccs!antel!mike
home: mike at boopsy.UUCP  or  uunet!utai!utgpu!maccs!boopsy!mike