[Dune] Parallel grid partitioning

[Eike Mueller]

Thanks a lot,

that's exactly what I was looking for and it solves my problem for YaspGrid.

Eike

Steffen Müthing wrote:
> Hello Eike,
> 
> Am 11.10.2011 um 18:17 schrieb Eike Mueller:
> 
>> Dear Dune-list,
>>
>> I wonder if someone could help me with these questions about partitioning my grids in parallel runs.
>>
>> The first is about a unit cube realised with YaspGrid. If I let Dune do the partitioning and run on 8 cores, it will split all three space dimensions into two, so I end up with 8 small cubes, each with half the sidelength of the initial cube. However, I want it to keep vertical columns together, so when using eight cores the x-direction should be split into four bits and the y dimension into two bits and the z-direction should be completely unsplit. The constructor of YaspGrid seems to take a load balancer as an argument but I could not find any more information on this in the documentation. Do I have to write my own loadbalancer and what class would I have to derive it from?
> 
> I am not really an expert on YaspGrid, but as far as I know, you have to write your own loadbalancer, which has to be
> derived from the class YLoadBalance (defined in dune/grid/yaspgrid/grids.hh:1021). Something like the following class
> should do the trick:
> 
> template<int d>
> class LoadBalancer
>   : public Dune::YLoadBalance<d>
> {
> public:
>   typedef Dune::FieldVector<int, d>  iTupel;
>   virtual void loadbalance (const iTupel& size, int P, iTupel& dims) const
>   {
>     dims = 1;
>     dims[0] = P; // set this for the direction in which you want to stripe
>   }
> };
> 
>> Second, I'm setting up a spherical shell with ALUGrid (see [1]). Again I want to keep vertical columns together and not split into the radial direction, so the sphere should be covered with eight patches of equal size.
>> So far I only managed to get the serial ALUGridFactory to work, if I run in parallel, do I have to do the decomposition myself and call inserVertex() and insertElement() on the appropriate processor or can I do the balancing afterwards? Or do I have to insert all vertices/elements on the master node?
> 
> Sorry, can't help you there....
> 
> Steffen
> 
>> Thank you very much for any ideas,
>>
>> Eike
>>
>> [1] http://people.bath.ac.uk/em459/dune.html
>>
>> _______________________________________________
>> Dune mailing list
>> Dune at dune-project.org
>> http://lists.dune-project.org/mailman/listinfo/dune
> 
> Steffen Müthing
> Universität Stuttgart
> Institut für Parallele und Verteilte Systeme
> Universitätsstr. 38
> 70569 Stuttgart
> Tel: +49 711 685 88429
> Fax: +49 711 685 88340
> Email: steffen.muething at ipvs.uni-stuttgart.de
> 
> 
> 
> 
> 
> 
> _______________________________________________
> Dune mailing list
> Dune at dune-project.org
> http://lists.dune-project.org/mailman/listinfo/dune
>