Atlas compiling causes havoc

[Vincent Habchi]

Jasper,

> MacPorts config is:

[…]

That’s not a configuration problem, it is just a matter of what exactly the port upgrade has done. Try to update manually (port -v install atlas +gcc45).

Atlas can take a very long time to build if you don’t choose one of the GCC compilers with x86_64 arch. Any other combination (use of clang, or non x86_64 build) triggers the timing mechanism: Atlas finds out by itself what is the best set of parameters for each kernel by compiling hundreds of combinations and measuring their efficiency. This is a long process (it took around five hours on the Lion Buildbot), but guarantees near optimality on a per machine (CPU, memory…) per compiler basis at the end.

If you use clang and build universal, for instance, compiling Atlas might take over ten hours if you have a Core2Duo machine.

Vincent