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Re: Changing the default 32-bit x86 arch for Fedora 12 (#2)



On 06/17/2009 03:00 PM, Richard W.M. Jones wrote:
On Wed, Jun 17, 2009 at 01:52:26PM -0400, Bill Nottingham wrote:
- Build all packages for i686 (this requires cmov)

This cuts out AMD Geode ...

and for what ...

               P4 2.4Ghz       Athlon 3400+    Core2Duo E6850  Atom N270
march=i686/   -1.1%           +2.0%           +0.9%           +0.6%
  mtune=generic
march=i586/   +0.3%           -0.3%           -0.2%           +1.3%
  mtune=atom
march=i686/   -1.5%           +1.2%           +0.5%           +1.7%
  mtune=atom

This just doesn't look worthwhile at all.

My proposal is that we actually start to 'downgrade' x86, start
compiling for baseline i386, and try to support people running Fedora
on really old hardware, through projects like the Minimal Platform
feature.

Richard Jones, Emerging Technologies, Red Hat  http://et.redhat.com/~rjones

Agreeing with Rich, what does this buy us?  Being generous, 1.7% means
you shaved 1 second off a 1 minute mp3 encode.  Perhaps measurement
accuracy is on the order of 0.5%?  And the P4 performance degrades;  Why
further cripple the slower chip?

This slight benefit doesn't seem worth the effort of re-doing the build
infrastructure and dropping/alienating older chip architectures.

-Bob Arendt


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