dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Tue, Feb 19, 2008 at 08:13:42PM +0100, Niclas Jansson wrote:
> On Mon, 18 Feb 2008 20:16:43 +0100
> Anders Logg <logg@xxxxxxxxx> wrote:
> 
> > On Mon, Feb 18, 2008 at 08:06:27PM +0100, Niclas Jansson wrote:
> > > On Mon, 18 Feb 2008 18:31:54 +0100
> > > Anders Logg <logg@xxxxxxxxx> wrote:
> > > 
> > > 
> > > > > We (Nicklas) have now a preliminary distributed parallel
> > > > > implementation running for Poisson and a Unicorn flow solver.
> > > > > The structure is still quite messy and the partitioning is based
> > > > > on Metis, but we expect it to be integrated with DOLFIN in the
> > > > > coming months, hopefully before the summer.
> > > > 
> > > > Could this be done in small pieces? I'm a little worried about
> > > > seeing big changesets that add things to the mesh classes.
> > > > 
> > > > > When the structure is more clear we can discuss on the mailing
> > > > > list how to best incorporate this into DOLFIN. Apart from the
> > > > > structure of the implementation we are also focusing on
> > > > > distributed local mesh refinement.
> > > > 
> > > > Great.
> > > > 
> > > > What is the difference from what we have now? Is it the same but
> > > > with a distributed mesh (so each processor just sees the local
> > > > part, not the whole mesh)? Or is it something different?
> > > > 
> > > 
> > > Yes, each processor only sees the local part. The entire problem is
> > > never represented on one processor. Preprocessing, assembly,
> > > solution and postprocessing are all done without
> > > gathering/scattering data to/from one processor.
> > > 
> > > The only modification to the mesh classes is a new class storing
> > > information about ghost points and vertex local to global mapping.
> > 
> > What about local-to-global mapping of edges, faces etc?
> 
> We haven't implement any of these mappings, mainly because our problems
> only uses dofs on vertices. However they should be fairly simple to add.

ok. I think storing a facet-to-facet mapping (as in the link I sent
earlier) should take care of everything.

-- 
Anders