2009/2/2 King InuYasha <ngompa13@xxxxxxxxx>: [snip] > Honestly, I think Fedora needs to stop > bottlenecking its performance by not optimizing its code for i586 or i686. I > would prefer the code to be optimized to i686 when built as RPMs. -march != -mtune. The code is already tuned for more modern CPUs. Allow me to repeat this: (loudly, not to be mean but because people seem to miss it) FEDORA x86 IS ALREADY OPTIMIZED FOR MODERN CPUS. mtune should result in the overwhelming majority of the performance difference with none of the compatibility issues. -march=i686 adds a single instruction of disputable value, cmov. In exchange for getting this one additional instruction it breaks compatibility with pentium, VIA C3 (Nehemiah has cmov, but eden does not; I have an eden600 board here which is only ~3 years old!) , AMD K6, etc and potential performance problems on Pentium 4. Do you have benchmarks that show given a constant -mtune that -march=i686 makes a material difference for any significant userspace apps vs -march=i586, if not why are you being so insistent and damning of the current compatible behavior? We know that -march=i686 will break compatibility for a small but measurable number of users (and potentially a larger unmeasurable number), do we know if we'll even get a measurable gain in exchange? We would see much more substantial gains from things like -msse2 & fpmath=sse but, unfortunately, unlike i586 there are a *lot* of systems out there (and still being sold) which do not have all the fancy instruction set extensions. Repeating myself here… When it comes down to it, we already have a "performance compiled" distribution: x86_64 which has every i686 knob turned on and then some. If you care about whatever really minute gain you'd get out of arch=i686, then you really should be looking for an x86_64 system. (The higher end atoms are quite attractive I hear…) -- fedora-devel-list mailing list fedora-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-devel-list