dolfin team mailing list archive

[Niclas Jansson <njansson@xxxxxx>]

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.


Niclas