Given the loud feedback, I've updated the proposal at:
https://fedoraproject.org/wiki/Features/F12X86Support
The revised proposal:
- Build all packages for i686 (this requires cmov)
- Optimize for Atom
Why?
- We don't really support i586 in any meaningful matter
- OLPC still works with base i686
- We are likely doing a mass rebuild for F-12 anyways, might as well switch
while we're doing it
- Atom is the only currently produced 32-bit x86 chip of note; optimize
for what's currently available
If you want numbers, I did some benchmarking of code [1] with various
build options on a variety of processors, with the F-11 gcc code. All
of these results are relative to a F-11 baseline of "-march=i586
-mtune=generic".
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
Bill
[1] gzip, bzip2, math simulation, mp3 encode/decode, ogg encode/decode
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