Mike, Thanks for the succinct and very clear explanation. I have come to many of the same conclusions. There are few apps which do benefit from -march=i686, but if one aims to increase performance for a given application other compiler optimizations will have a more dramatic benefit.
Apps which use lots of floating point code can <<sometimes>> benefit from options like -ffast-math. My short bit of testing shows -march=athlon or -march=athlon-xp makes a bigger difference on 8.0(because of gcc 3.2), than variations on x86. Simply upgrading from gcc 2.96 from 3.2 probably gains the most. :O YMMV Perhaps this should be posted on redhat.com and/or in the user docs.. Peter
