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Re: RFC: Optimizing for 386



Once upon a time, Joseph D. Wagner <technojoecoolusa charter net> said:
> OK, let me make clarify what I said.
> 
> AMENDED: All IA32 RPM's are optimized for 386 architecture.

And that is still wrong.  All FC i386 arch RPMs are optimized for either
i686 (up through FC2) or P4 (starting with FC3).

Some important RPMs (kernel, glibc, openssl) where the difference has
been proven come with i686 arch RPMs as well as i386 arch RPMs.  Some
other RPMs have code that detects i386 vs. i686 vs. Athlon (really
"regular" vs. MMX/SSE/etc.) at runtime and uses the best available.

Whenever this comes up, people make some claims of improvement if the
instruction set used is i686 instead of i386, but the challenge is to
prove it.  The only valid way to prove it is to do some type of
repeatable benchmark of real applications with Fedora Core installed as
distributed.  Then rebuild the packages from the same source with the
only change being i686 arch instead of i386 arch and retest.  Anything
else is not a valid test of the gain Fedora could see in switching from
i386 arch to i686 arch.

If someone takes the time to prove the point (and it is proven that the
pain is worth the gain), you will get results; people will listen.
Until it is proven, you'll just get told to RTFA.  The burden of proof
is on those asking for the change.

-- 
Chris Adams <cmadams hiwaay net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble.


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