[Dune-devel] Grid-Entity ownership in distributed ALUGrid or UGGrid

[Markus Blatt]

Hi,

my 2 cents

On Sat, Oct 09, 2021 at 11:16:57AM +0200, Simon Praetorius wrote:
> [...]
>in combination with, e.g., the dune-istl data-structures. When working 
>on some examples, I noticed that one of the first steps seems always 
>to be to identify unique ownership of grid entities, i.e., can we 
>assign uniquely a processor rank that "owns" a given grid entity or 
>can we tell whether we are the master over a local entity. This is the 
>basis for building up a communication pattern for the actual DOFs in a 
>discretization.

I am a bit unsure whether the assumption really holds for all grids and
discretizations. I think a clear ownership (as in partition information into
owned and maybe copy) only exists on the entities that were load balanced.
On most grids these might be the codim-0 entities. For the rest such an ownership
concept is rather artifical/arbitrary (at least for a subset of the entities).
Hence something has to be computed if that is needed. Of course we can demand
from grids that they need to do this (if requested).

Also please be aware that there are certain discretizations and methods that
demand a certain type of partitioning that is different from the default dune-istl one.

There are discretizations that attach data to different entity types.

I am not saying that we shouldn't do it, but in all generality this might become
quite some work.

Markus
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Dr. Markus Blatt - HPC-Simulation-Software & Services http://www.dr-blatt.de
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