RPM Builds and System Optimization

Steve Snyder swsnyder at insightbb.com
Thu Aug 26 22:42:30 UTC 2004


On Thursday 26 August 2004 11:40 am, Alexander Dalloz wrote:
[snip]
> This is an alway returning question, asked time by time. The RPMs of
> Fedora Core are build for arch i386 with optimization enabled for P4
> CPU. So they are able to run on all i386 platform and will use special
> instructions on newer CPUs.

Yes, this comes up all the time.  Unless they changed tp P4 optimization in FC3, though, the build flags are what they've aleays been:

  --march=i386 -mcpu=i686

That is, 386-compatible, but instruction organization optimized for a Pentium Pro/II/II.

How much improvement you'd see by building with "-march=pentium4" is left as an exercise for the reader.

Also, I wonder about the quality of the P4 GCC optimizations in general.  Back when the current version was 3.2.x I read on the GCC mailing list that the P4 optimization probably wouldn't be fully realized until v3.4.  As the default compile for FC2 is v3.3.3, I wonder if the P4-specific handling is completely baked.





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