Athlon Incompatible Packages

[Jakub Jelinek]

On Tue, Feb 24, 2004 at 12:13:54AM -1000, Warren Togami wrote:
> I remember reading some comparative benchmarks of gcc-2.95 and gcc-3.2.x
> somewhere that showed relative effects of compiling stuff for different
> architectures.  IIRC, back during 2.95 compiling for athlon did make a
> large difference when compared to i386, but the gap narrowed significantly
> with gcc-3.2.x.  So Gentoo was perhaps effective in optimization back
> then, but the reasons for doing so have quickly gone away.

Plus Fedora is compiled (tuned) for i686, not i386 (just doesn't use i486+ only
instructions, from which only cmov* is important for compiler generated code
unless you use SSE2 math (the rest are just atomic instructions)).
cmov is a win on some CPUs and for some programs, but is a slight lose on
others, so unless you want to spend huge time not only rebuilding, but also
benchmarking every single application to see what options are best, you are
just wasting your time with rebuilding.
Athlons generally run i686 tuned code very quickly, the differences between
-mtune=i686 and -mtune=athlon will be minimal (and nothing guarantees you
that for some program you actually don't loose performance with -mtune=athlon
compared to -mtune=i686).

	Jakub