[gmx-users] optimization of gromacs 4.0.5 on AIX Power6

[Silvia Giuliani]

Dear All

Has anybody tried version 4.0.5 on an IBM Power6 (4.7Ghz) cluster?
We have installed the program with the following configure options 
(using fftw we installed separately):

./configure --with-fft=fftw2 --enable-mpi --enable-float CC=mpcc_r 
F77=mpxlf_r CXX=mpCC_r CFLAGS="-O3 -qarch=pwr6 -qtune=pwr6 -qcpluscmt"

It compiles and works but the performance is poor compared to our 
Opteron  Cluster (2.6Ghz)
For example with 8 procs for a small protein in water we get 5.8ns/+day 
compared to 9.6 ns/day on the Linux cluster, which is a bit disappointing.
Since there alot of compiler options to play with we would be grateful 
if somebody who has already found a good set would share them with us.

best wishes
Silvia Giuliani