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Re: Athlon optimized KDE build

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Hi Magnus,

I used to optimize my own codes with -march=i686 but I tried -march=k6 and it 
doesn't seem to perform badly. Usually the sub architecture flags are used to 
direct peephole optimizations and allow generation of specific instructions 
(which would be incompatible with other subarchs). So, if there is a faster 
way to accomplish something,  it is used on that specific architecture. I 
didn't program on i386 assembly beyond 486 so I can't really (from first hand 
experience) tell but I assume such differences do exist. The most notable of 
those differences is the existence of certain "multimedia" instruction sets 
which provide "fake" vector operations (for real vector operations you need 
multiple memory "buses") Anyway, no need to go into that. For an Athlon 
processor gcc-2.95 offers you k6 and i686. Both do a host optimizations, and 
I would expect to see speedup over i386 for both of these architectures. Of 
course if you can point to an extensive benchmark of these two sub-archs on 
application codes I would be pleased. I haven't seen such a study. It is 
indeed possible that i686 is better for scientific codes but again I wouldn't 
bet on that. gcc-3.x gives us a k7 sub architecture which hopefully yields a 
better performance than both :) So, when g++ starts working properly we 
should switch to it.

So much for stating the obvious.

Now about the debian packaging in CVS, the build that I did is quite 
different. It doesn't intervene with the debian system in any way, therefore 
you don't have to remove any KDE 2 packages. Plus, it is well optimized.
In fact, when you try to build KDE 3 debian packages from CVS, you might find 
that the end result might not be entirely satisfactory, that is if you manage 
to get an end result.

BTW, I'm going to do even more optimized builds if you're interested. I'm 
thinking of trying out fast malloc which is said to cut down application 
startup time. Even if it's hard to share these huge binaries, we can share 


- -- 
Eray Ozkural (exa) <erayo@cs.bilkent.edu.tr>
Comp. Sci. Dept., Bilkent University, Ankara
www: http://www.cs.bilkent.edu.tr/~erayo
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