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From: bradbury@oracle.UUCP (Robert Bradbury)
Newsgroups: comp.sys.ibm.pc
Subject: Microport 386 UNIX 5.3 Rel 2.1 speed questions
Message-ID: <346@oracle.UUCP>
Date: Mon, 16-Nov-87 23:27:29 EST
Article-I.D.: oracle.346
Posted: Mon Nov 16 23:27:29 1987
Date-Received: Thu, 19-Nov-87 06:48:18 EST
Organization: Oracle Corporation, Belmont, CA
Lines: 35
Keywords: Microport, Compaq 386, System 5.3, drystones

I've just installed Microport Unix 5.3 Rel 2.1 on my Compaq 386.
I'm puzzled about the speed of the machine.  Microport UNIX 5.2
on the 386 (in 286 mode) gives a Drystone rating of 3275 with
the UNIX compiler and 3500 with the Metaware compiler.  The 5.3
release in 386 mode gives a Drystone rating of 1652 (no-reg)
and 1773 (reg).

Why does the 386 run slower than the 286?

Another test:
	time cat < /dev/null
gives a real time of .2 sec on the 286 and .4 sec on the 386.
I thought this might be due to virtual memory/shared library
overhead but the drystone results indicate that the 386 is slower
for compute-bound operations.

My drystone results were even worse before I discovered they
had changed HZ to 100 on the 386 (from 60 on the 286).
(The interesting question is whether the times() call returns
 60 HZ ticks for 286 programs running on the 386 (or whether
 upwards compatibility is a pipe-dream).)

My general impression is that the 386 release "seems" slower.
Has anyone else found this to be true and are there any
explanations?  Is this a general problem with 5.3?
Could it be related to shared libraries or virtual memory
or does it involve the 80386 architecture in some way?

Does anyone have any comparisons of 286 vs 386 Xenix or
Interactive Systems UNIX?

-- 
Robert Bradbury
Oracle Corporation
(206) 364-1442                            hplabs!oracle!bradbury