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

[Adam Miller]

+1 For the i686 with atom optimizations. This seems like a solid suggestion
and Gregory's argument seems logical.

-Adam
(From my G1)

On Jun 23, 2009 11:49 PM, "Gregory Maxwell" <gmaxwell at gmail.com> wrote:

On Tue, Jun 23, 2009 at 4:19 PM, Clemens Eisserer<linuxhippy at gmail.com>
wrote: >> 1) Optimizing for ...
Fedora x86_64 is the solution for good performance for those systems.
The difference between 32bit mode and 64bit mode dwarfs all the little
compiler tweaks we could discuss.

Optimizing for atom makes sense because it's the most modern hardware
which doesn't have a higher performing alternative than the 32bit
build.

Moreover, as an in-order core it atom should gain more from
optimization than most cpus and generally optimizations for atom are
harmless or even beneficial for other CPUs, while optimization for
highly out of order CPUs can be devastating for in-order cores. As you
can see in Bill's post upthread optimizing for atom is mildly
beneficial even to P4.

Amusingly, on my own code at least -mtune=atom produces significantly
faster code than -mtune=geode on my geode LX.

P4 is pretty much a lost cause. The move to i686 from i586 itself will
make P4 slower, while helping most everything else by about the same
margin that it hurt p4. Optimizing for P4 will probably hurt
everything, certainly atom.

Atom systems are frequently battery powered, so improvements there can
also to increased battery life.  P4, OTOH, already requires a locally
installed atomic power plant so energy isn't an issue there.

...

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