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From: Michael Erdmann <boavista@berlin.snafu.de>
Subject: Re: Ada for OS/2 (was Re: Linux faster than OS/2...)
Date: 1997/07/06
Message-ID: <33BFD446.205A@berlin.snafu.de>#1/1
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References: <5ovqj1$4ul$1@unlisys.unlisys.net>
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Organization: Unlimited Surprise Systems, Berlin
Reply-To: boavista@berlin.snafu.de
Newsgroups: 
 comp.os.os2.setup.misc,comp.os.os2.programmer.misc,comp.os.os2.programmer.oop,comp.lang.ada
Date: 1997-07-06T00:00:00+00:00
List-Id: <comp.lang.ada>


Robert Dewar wrote:
> 
> Michael said
> 
> <<I have done this today. It seems now to work a bit faster.>>
> 
> That's not very convincing :-)
> Did you actually measure the difference.
> I tried the -pipe and it made no difference at all to the
> compilation speed of several examples I tried.
I have repeated the measurement. The difference is not measurable,
what happend was more simple. I did increase my ram cache from
1.5M to 2M and this caused most of the enhancement in the speed.

> 
> But a lot depends on your setup. In my setup, I have 80 megs and never
> swap, so in fact disk IO is completely overlapped (I tried an interesting
> experiment which was to put
> 
> sources, objects, temp files, ali files
> 
> for the library all in a RAM disk, and compile the library. It took,
> within measurable accuracy EXACTLY the same time as using a disk with
> the normal HPFS cache.
> 
I dont have 80 MB, but i allready thought about installing a ram disk
for the same purpose.

> That's why I don't think -pipe will help. If you have a decent amount
> of RAM and a 2 meg cache, then the temporary files get written to the
> cache, and read from the cache. Sure, they get written to disk as well,
> but these are lazy writes from the cache which can be completely
> overlapped with computation.
I agree on this and i am not going to install any ramsdisk.

By the way i have redone some measurement based upon a software package 
called rudstone. I did take the sources from the 1995 Ada CDROM from
Walnut Creek and done the same measurements:

		Compilation+Build	Execution 
	OS/2            150 sec		   97 
	Linux		135 sec		  114

Compiling is slower in OS/2 but the execution time for the benchmark
is smaler, meaning better performance. 
What i understood so far, i have to accept some performance degrade
for the compilation in favor of the OS/2 features, but the performance 
of programms is not automaticaly less good then with Linux. 
As a result i decided to stay with OS/2 instead of switching to Linux.

Michael