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Mail Archives: djgpp/2000/03/11/08:44:40

Date: Sat, 11 Mar 2000 18:46:18 +0600 (LKT)
From: Kalum Somaratna aka Grendel <evilgrendel AT gmx DOT net>
X-Sender: root AT darkstar DOT grendel DOT net
To: djgpp AT delorie DOT com
Subject: Re: AMD processors and assembly language
In-Reply-To: <01JMVKC89LSI9ASAX4@SLU.EDU>
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On Fri, 10 Mar 2000 GAMMELJL AT SLU DOT EDU wrote:

>      I did get work on the machine with an AMD processor and found
> (as several had pointed out) that the problem I was having had nothing
> to with the AMD chip but rather had to do with the new version of djgpp
> (not the latest but the one before the latest) being used on that machine.

Yes this was the problem, and its great that you've sorted it out.


>      Everything works fine after that.  What one learns is that the
> AMD processor is faster than what one would expect from the clock speed
> (megahertz) 

Certainly true. AFAIK My K7 athlon running at 500 mhz certainly thrashes
any Wintel 500 mhz chip. Actually I bet that it even outperforms the
Wintel 600 mhz chips even. And even better I can overclock the 500 up to
800 mhz IIRC..

>provided one does not optimizing and does not use assembly
> language.  

I am a bit confused here. Certainly assembly code will run slower than c
code if it is badly written. As there is no way that good hand optimized
assembly can be slooow, except if they are written for a diferrent CPU
etc.

on a side note, I find that there is less reason to write assembly as most
of the modern day compilers do a superb job in producing effecient C code
which can inturn be compiler optimized for specific architectures (386
,686 etc). 

So a good way is to write as much of the code as possible in C profile it,
identify the bottlenecks and _then_ decide to rewrite the slow code in
assembly.

>The executables run much faster when one uses assembly language
> and optimization -O2.  

Now you say that the exes run faster when using assembly???? Could you
please clarify this.

> in line with what the clock speed suggests, with the Intel processor
> a little faster.

No way that this is possible :-)  K7 athlons outperform wintel chips on
most aspects especially on the floating point handling.
 


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