Xref: utzoo comp.sys.ibm.pc:28888 comp.sys.amiga:33889
Path: utzoo!attcan!uunet!cs.utexas.edu!husc6!ogccse!blake!uw-beaver!ssc-vax!coy
From: coy@ssc-vax.UUCP (Stephen B Coy)
Newsgroups: comp.sys.ibm.pc,comp.sys.amiga
Subject: Re: OS/2 vs AmigaDOS
Summary: some numbers...
Message-ID: <2655@ssc-vax.UUCP>
Date: 16 May 89 03:52:41 GMT
References: <20694@iuvax.cs.indiana.edu>
Organization: Boeing Aerospace Corp., Seattle WA
Lines: 58



In article <20694@iuvax.cs.indiana.edu>, bobmon@iuvax.cs.indiana.edu (RAMontante) writes:
> coy@ssc-vax.UUCP (Stephen B Coy) <2649@ssc-vax.UUCP> :
> 	[MIPS tests 25MHz '386 boxes.  In...]
> -doing their benchmarks they test the systems running 3 different
> -OS's; DOS, Xenix, and OS/2.  Looking at the benchmark results I get
> -the impression that system performance under OS/2 is about 40% less
> -than under DOS.  How good can resource management be if it consumes
> -40% of the CPU? 
> 
> 40% sounds a bit high,

OK.  Here's the numbers I was referring to:

The benchmark program is the current version of dhrystones.  The
benchmark was run both with and without register varaibles.  Only
one DOS timing is given since the numbers were the same for both
cases.  Under OS/2 the 1st number is without register variables, the
2nd is with.  All the systems are 25Mhz 386's.

system				 DOS		    OS/2 

ACER 1100/25			11970		5925	6153
ALR FlexCache 25 286		12281		6486	6760
Compac Deskpro 386/25		11203		5783	6000
DEL System 325			11671		6000	6153
Everex Step 386/25		12445		6666	6956
IBM PS/2 Model 70A21		11745		6486	6760

Well, the way I count it the overhead is from 42.4% to 50.5%.

> but the contrast to MSDOS isn't really fair.  MSDOS
> doesn't have to do *any* resource management, in the sense that it needn't
> keep track of which process has a resource (since there's only one process
> at any time).  On the other hand, every TSR has to do its own management
> in terms of checking whether it's safe to do disk I/O or whatever.

Sorry, I didn't make myself clear.  I know that MS-DOS is doing
absolutely nothing.  Therefore I looked at the DOS numbers as being
the absolute best you could get out of the system ie the bare-bones,
down-to-the-metal raw cpu power available.  Then, looking at the
OS/2 numbers, I saw that up to half of that cpu power was lost to
system overhead.  And I thought that stunk.

> The amount of CPU spent in overhead is also a function of system load.
> It's possible for one OS to be extremely good with a few processes but
> degrade badly as it overloads, while another OS can be a bit worse at low
> loads but stay pretty much the same until its memory chips begin to smoke.

But an OS that starts with 40% to 50%?!?  Unless you think that the
good folks at MIPS magazine were generating Mandelbrot images in the
background while running the benchmarks.  :-)

Stephen Coy
uw-beaver!ssc-vax!coy