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Subject: Re: [OMPI users] install intel mac with Laopard
From: Michael (mklus_at_[hidden])
Date: 2008-04-25 14:03:28

On Apr 24, 2008, at 10:48 AM, Jeff Squyres (jsquyres) wrote:

> You probably want to use all the intel compilers, not just ifort.
> CC=icc
> CXX=icpc
> FC=ifort
> F77=ifort

I have long used gcc and ifort on 64-bit Linux (since SUSE did 64-bit
Linux on AMD Opterons), I don't see a good reason why OS X should be
be/remain a problem.

There are very major reasons to use gcc and ifort. It works and
buying a bunch of ifort C licenses is an unnecessary expense, unless
there is some type of speed advantage to compiling OpenMPI with the
Intel compilers instead of gcc.

Given that we have very little C code that requires a highly optimized
compiler for the latest Intel Xeon we will continue to use gcc when
building OpenMPI. However, given that ifort generates code that is
7.7 times faster under Linux than that generated by latest g95 and
gfortran in my tests on a 5300-series Xeon (first dual quad 3.0 GHz
Mac Pro) we will also continue using ifort for the foreseeable future.

Strangely g95 is 2.7 times faster under OS X (with virus-checking)
than under g95 under Linux on a 5100-series Xeon (first quad 2.66 GHz
Mac Pro). This is something I will test again with Intel's OS X
Fortran compiler against their Linux compiler to see if there is a
difference there.