[gmx-developers] Gromacs on an IBM Power machine

Berk Hess hess at kth.se
Thu Jun 18 16:03:50 CEST 2015


It looks like the few kernels routines needed for the CPU non-bonded 
kernels are not present (yet). Erik Lindahl is the one who implemented 
the SIMD for Power8, I don't know if he has these routines already.
But with a GPU this doesn't matter, since those kernels will run on the 
GPU. All other things on the CPU should use Power8 SIMD.



On 06/18/2015 02:50 PM, Baker D.J. wrote:
> Hello,
> I’m not sure that this is the correct place to send my question, 
> however please bear with me and help me to redirect my enquiry if 
> necessary.
> We recently received delivery of two Power8 machines—one of the 
> machines has a K40 GPU installed. I have read that interesting reports 
> that Gromacs performs well on Power8 systems, especially if there’s a 
> GPU card available. I have been doing some experiments, and so far 
> I’ve have been very disappointed by the performance of Gromacs. At 
> this stage I am just working on one of the “water” examples (1536). I 
> am working with the very latest gromacs (5.1) and I have tried 
> configuring with GMX_SIMD=IBM_VSX, however when I try a parallel run I 
> still get this warning:
> WARNING: Using the slow plain C kernels. This should
> not happen during routine usage on supported platforms.
> Could someone please advise how I should configure and install Gromacs 
> to get the best out of our Power8 machines.
> Best regards,
> David.

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