[gmx-developers] electrostatic forces and domain decomposition

[Roland Schulz]

Hi,

On Sun, Jun 26, 2011 at 8:31 AM, Dommert Florian <
dommert at icp.uni-stuttgart.de> wrote:
>
> with the current release-4-5-patches branch unexpected large
> electrostatic forces arise when using PME and MPI in combination with
> domain decomposition. I tried to attach a
> small test case with a water box of about 4000 molecules and a
> corresponding mdp, top, itp, and gro file, but it was too large. For
> particle decomposition
> with different numbers of processes everything is fine as well as for a
> run with a single process and DD. However using multiple processes and
> DD I obtain forces around 10^10, though they should be around 10^3.
>
> For the testruns I compiled gromacs with cmake on a
> Ubuntu 10.4 platform with a 2.6.39-rc6+ kernel using gcc4.4.3 and
> OpenMPI 1.4.3 and fftw3.2.2
> and a Rocks Cluster with a 2.6.18-164.6.1.el5 kernel and the same
> compiler, MPI and fftw3 version. On both systems I obtain the strange
> behaviour.
>
> When I got back to the commit with SHA1 ID
> e5eb052ebf35e4b778f7a3908463a68a2ef6faee, merge by merge,
> everything is fine again.
>

What do you mean merge by merge? Could you do a git bisect?

Roland

>
>
> /Flo
> --
> Florian Dommert
> Dipl. - Phys.
>
> Institute for Computational Physics
> University Stuttgart
>
> Pfaffenwaldring 27
> 70569 Stuttgart
>
> EMail: dommert at icp.uni-stuttgart.de
> Homepage: http://www.icp.uni-stuttgart.de/~icp/Florian_Dommert
>
> Tel.: +49 - (0)711 - 68563613
> Fax.: +49 - (0)711 - 68563658
>
>


-- 
ORNL/UT Center for Molecular Biophysics cmb.ornl.gov
865-241-1537, ORNL PO BOX 2008 MS6309
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