dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Thu, Sep 18, 2008 at 10:18:13AM +0200, Anders Logg wrote:
> On Thu, Sep 18, 2008 at 08:53:15AM +0100, Garth N. Wells wrote:
> > 
> > 
> > Niclas Jansson wrote:
> > > Garth N. Wells wrote:
> > >>
> > >> Niclas Jansson wrote:
> > >>>
> > >>>>>> Sounds good. Can you submit this in one or more patches, starting 
> > >>>>>> with
> > >>>>>> the parallel XML parser?
> > >>>>>>
> > >>> Finally, the parallel XML parser.
> > >>>
> > >>
> > >> Could you create a bundle against the dolfin-dev tip and re-send it? The
> > >> bundle was created against a relatively old dolfin-dev which makes
> > >> merging non-trivial.
> > >>
> > >> Garth
> > >>
> > > 
> > > This one should work, hopefully.
> > >
> > 
> > Thanks. I've just pushed it to dolfin-dev.
> > 
> > It would be good if all interseted parties could take a look and provide 
> > feedback.
> > 
> > Garth
> 
> I will look at it later today.

I have started looking at the code. It seems to work fine, but it will
take me a while to get through it.

It would be helpful if you could add some more comments. There are
large chunks of uncommented code for example in PXMLMesh::closeMesh.

I also wonder about the following in PXMLMesh::readVertices:

  const uint L = floor( (real) num_vertices / (real) num_processes);
  const uint R = num_vertices % num_processes;
  const uint num_local = (num_vertices + num_processes -
  process_number - 1) / num_processes;
  
  start_index = process_number * L + std::min(process_number, R);
  end_index = start_index + ( num_local - 1);

I think I can guess what it does, but does it have to be this
complicated? Isn't it enough to do something like

  const uint n = num_vertices / num_processors;
  start_index = n*process_number;
  end_index = start_index + n;

and then a fix for the last processor:

  if (process_number == num_processors - 1)
    end_index = num_vertices;

?

-- 
Anders

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