Compiling for CPU (was Re: Performance testing (pass 1))

[Rick Johnson]

ByteEnable wrote:

>>1. If Open Source writes better software; then why is it fatter and 
>>slower?
>>
>>2. Is any one at RHL working on desktop performance?
>>
>>These are some of the sugestione that I may need to answe to when I 
>>present this and further data to my managers. Gys... what should I say?

One question I've always had is why Red Hat still compiles for i386 
(march=i386 mcpu=i686 - ok, so they get i686 instruction ordering)? Once 
upon a time, I rebuilt my entire RH 7.3 tree and a good portion of my RH 
8.0 tree for i686 and/or athlon. I've also run Gentoo, compiled for 
Athlon XP, which isn't as solid of a comparison, but is still a "Linux" 
general comparison. In both Red Hat cases, there was an appreciable 
difference, especially in X GUI "redraw" speed and application start 
times. This was without prelinking. With prelinking and compiler 
optimizations, it may be possible to bring these speeds much closer to 
the "other brand" on the comparison.

Not to pit distros, but Mandrake compiles for i586 by default, though 
they don't really give out any i686 or athlon specific packages (last I 
checked). Given that Red Hat's minimum specd hardware is a Pentium class 
machine with 64MB for text, and a PII 400 with 128MB more more for GUI 
use, what would we have to lose by changing the default to compile as 
march=i586 and mcpu=i686, or providing i686 versions of core components 
of XFree86? I'm sure it "throws out" the few who like to build the 
distro for 386 and 486 machines, but I feel the majority would benefit 
and the minority could simply rebuild the SRPMs for i386 for their 
specific application (would be a handful of packages at best since those 
types of machiens probably wouldn't be running full-blown Gnome or KDE 
desktops, but perhaps browser kiosks at best.

Thoughts?
-Rick
-- 
Rick Johnson, RHCE #807302311706007 - rjohnson at medata.com
Linux/Network Administrator - Medata, Inc. (from home)
PGP Public Key: https://mail.medata.com/pgp/rjohnson.asc