[gmx-users] Gromacs on an IBM Power8

[Baker D.J.]

Hello,

I would appreciate advice on running gromacs on a Power8 machine, please. I recently downloaded and installed gromacs v2016 on one of our IBM Power8 machines. I understand that this version of gromacs has support for Power8 machines and it certainly performs a great deal better than earlier versions. So that is progress. On the other hand I wonder if the Power8 could do better. I used one of the gromacs benchmarks (case A) supplied by PRACE and ran the following command on the Power8..

gmx mdrun -ntomp 8 -ntmpi 24 -s ion_channel.tpr -maxh 0.50 -resethway -noconfout -nsteps 10000 -g logfile -nb cpu

In other words there are 24 cores and I turned on SMT=8. Using that configuration and the above command the performance is about the same as on a 16 core Sandybridge node...

Performance in ns/day
SandyBridge (16 cores) - 11.23
Power8 (24 cores)          -- 11.82
Power8 (using 2 gpus)  -- 28.34

That's compiling with the GNU compiler v4.9.1. Should I be able to do better on the Power8 with a different/later compiler and/or different runtime settings?

Best regards,
David