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NONMEM with the Intel fortran compiler with non-Intel (AMD) processors

From: Bob Leary <bleary>
Date: Tue, 5 Jan 2010 11:00:07 -0500

The following may be of interest to anyone running NM with the Intel =
compiler on
an AMD or other non-Intel processor. This apparently
has come to light with Intel's recent $1.25 billion antitrust settlement =
to AMD . The FTC is currently
looking into the Intel compiler issue and may require further action on =
Intel's part to correct its
'defective' compiler , which deliberately cripples performance on =
non-Intel chips. The
effect is fairly large - improvements of about 50% in performance are =
observed with
the AMD processors when the compiler is tricked into thinking it is =
compiling for an Intel processor.
See http://www.agner.org/optimize/blog/read.php?i=49 for a more =
complete version - here is an excerpt:
"Many software programmers consider Intel's compiler the best optimizing =
compiler on the market, and it is often the preferred compiler for the =
most critical applications. Likewise, Intel is supplying a lot of highly =
optimized function libraries for many different technical and scientific =
applications. In many cases, there are no good alternatives to Intel's =
function libraries.
Unfortunately, software compiled with the Intel compiler or the Intel =
function libraries has inferior performance on AMD and VIA processors. =
The reason is that the compiler or library can make multiple versions of =
a piece of code, each optimized for a certain processor and instruction =
set, for example SSE2, SSE3, etc. The system includes a function that =
detects which type of CPU it is running on and chooses the optimal code =
path for that CPU. This is called a CPU dispatcher. However, the Intel =
CPU dispatcher does not only check which instruction set is supported by =
the CPU, it also checks the vendor ID string. If the vendor string says =
"GenuineIntel" then it uses the optimal code path. If the CPU is not =
from Intel then, in most cases, it will run the slowest possible version =
of the code, even if the CPU is fully compatible with a better version."


Robert H. Leary, PhD
Fellow

Pharsight - A Certara(tm) Company
5625 Dillard Dr., Suite 205
Cary, NC 27511

Phone/Voice Mail: (919) 852-4625, Fax: (919) 859-6871
Email: bleary

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Received on Tue Jan 05 2010 - 11:00:07 EST

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