AMBER Archive (2008)

Subject: RE: AMBER: PGI amber9 problems

From: Ross Walker (
Date: Fri May 16 2008 - 13:06:14 CDT

Hi Lorenzo,

> I fixed everything..the problem was that the configure script
> (the command was "configure -nopar -opteron -verbose pgf90")
> writes wrong compiler flags in config.h:
> FFLAGS= -tp p7 (intel pentium 4)....instead of -tp x64 (opteron + Intel
> IA32/EM64T). Also k8-32 would have been appopriate for an AMD (32 bit).

Be very very careful here. The -tp p7 flag is in there deliberately, even on
Opteron, for the Portland group compilers because at the time AMBER 9 was
released there were several bugs in the Portland group compilers that led to
incorrect answers if you compiled a 64 bit (x86_64) version of the code. We
could not work around these bugs and so the -tp p7 was added to force 32 bit
compilation. This should work on all x86_64 chips, both Intel and AMD. I
doubt there is much performance difference between k8-32 and -tp p7 on an
Opteron but you could try it.

So if you want to use the x64 flag for a 64 bit executable please double
check that ALL of the test cases pass, both serial and parallel. If you find
that everything passes please let me know what Portland group compiler you
have and we can perhaps update the configure script.

All the best

|\oss Walker

| Assistant Research Professor |
| San Diego Supercomputer Center |
| Tel: +1 858 822 0854 | EMail:- |
| | PGP Key available on request |

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