AMBER: 64-bit pgf90 revisited

From: Ingvar Lagerstedt <>
Date: Tue, 29 May 2007 09:39:07 +0100


There have been some interest in the past to get a working build in
64-bit mode with pgf90, the current recomendation is to either use pgf90
in 32-bit mode, or switch to another compiler like ifort.

By lowering the optimization level for the file
src/sander/qm_link_atoms.f all tests pass except for off by one errors.
I also noticed that at least for one of the tests
(qmmm2/neb_gb/neb_link_atoms), it was possible to get the test to pass
by adding some "Write" statements in position_link_atoms around line
175-180. It looks like the indices for the I have tried pgf90 versions
6.1-1 and 7.0-2. The only OS's I have tried are:
SUSE LINUX Enterprise Server 9 (x86_64)
SUSE LINUX 10.0 (X86-64)

I have not looked at what the possible performance hit is by lowering
the optimization level for this file.

These are compile flags I used:
FOPTFLAGS= -O3 -fastsse -Mvect=nosse -Mcache_align -tp k8-64e
FOPTFLAGS= -O3 -fastsse -Mvect=nosse -Mcache_align -tp p7-64

I may be possible to remove the platform specific flag, tp, so that the
same settings can be used regardless of hardware, someone more
experienced with the pgf90 compiler can comment on that. I just wanted
to ensure 64-bit builds.

Hope this helps,

Ingvar Lagerstedt, Scientist
ClearSpeed Technology plc,
Tel: +44 117 317 2055, Fax: +44 117 317 2002
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Received on Wed May 30 2007 - 06:07:26 PDT
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