Xref: utzoo comp.sys.ibm.pc:28944 comp.sys.amiga:33987
Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!oliveb!amiga!cbmvax!daveh
From: daveh@cbmvax.UUCP (Dave Haynie)
Newsgroups: comp.sys.ibm.pc,comp.sys.amiga
Subject: Re: OS/2 vs AmigaDOS
Message-ID: <6910@cbmvax.UUCP>
Date: 17 May 89 22:34:14 GMT
References: <2656@ssc-vax.UUCP>
Organization: Commodore Technology, West Chester, PA
Lines: 36

in article <2656@ssc-vax.UUCP>, coy@ssc-vax.UUCP (Stephen B Coy) says:
> Xref: cbmvax comp.sys.ibm.pc:33486 comp.sys.amiga:36543

> The systems benchmarked were all "fully loaded" and as such had
> plenty of memory to run the dhrystones benchmark with megs to spare.

I think part of the reason they get much better results with Dhrystone
on the MS-DOS vs. OS/2 systems may be nothing more than caching 
effects.  Most of those high-end 25Mhz and 33MHz 80386 systems have
between 16k and 64k of external cache.  Here on my Amiga, Dhrystone 2.1
comes out at around 20k, certainly most if not all of which would fit
in the cache of these machines.  Add OS/2, and if, during the course
of any Dhrystone run, you get a context switch, I'll bet you end up
dumping cache on the switch (UNIX would have to as well, AmigaOS wouldn't)
and greatly slowing the system.  While the test does show the absolute
maximum speed each machine can do with a Dhrystone, it's not very telling
in real life situations.  I haven't seen MIPS mention cache effects in
detail on their benchmark explanations, but they otherwise seem to handle
them pretty well.  This is also a good explanation as to why their best
MS-DOS machines run faster Dhrystones than anything short of a good RISC
system, but fast '030 machines do better under UNIX than the same fast
'386 machines under UNIX.

> I too would like to see some other comparisons done.  If anyone has
> any, please post.

I'm seeing around 7000 Dhrystones on an A2630 equipped A2000 and the best
set of Lattice 5.02 compiler switches.  With a fat external cache at the
same speed, this might come close to being doubled.

> Stephen Coy
> uw-beaver!ssc-vax!coy
-- 
Dave Haynie  "The 32 Bit Guy"     Commodore-Amiga  "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: D-DAVE H     BIX: hazy
              Amiga -- It's not just a job, it's an obsession