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Don't use pentium4 for AMD64!

Posted by: Anonymous Coward on June 17, 2005 04:52 AM
Compiling with march=pentium4 does not mean that it uses sse2 and mmx and what not, there are different gcc flags for that. It means the code is optimized for a pentium4 which for 1 is a 32bit CPU so it won't even compile in the 64bit version of whatever functions are being called. Additionally, the pentium4 has a very long pipeline and code optimized for a long pipeline will run slower on a cpu with a short pipeline, say an AMD64.

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