sieve-dev Manual mesh distrition

[Shi Jin]

Hi there,

I brought up this question earlier  about using the chaco graph partitioner
to partition my mesh.  It worked for that time being. Now I wanted to pursue
it in a better way to follow Matt's suggestion on directly partition the
graph to my own specific need. Here I quote Matt

*"If you have to have a certain partition for the algorithm,
why not just provide that partition yourself instead of trying
to force Chaco to do it. All the partitioner does is provide a
list of which elements are in which partition, and then I do
the rest. You can just run through all the elements, dumping them
in the bin you want so that particle checks work. Then all the
connections, communication, etc. will be worked out automatically."*

I further looked into the mesh source code and found that this is actually
quite easy to do.
All I need to do is to provide an array called assignment where each entry
provides the rank of process the element belongs to.
This way, I don't have to ask Chaco to do the partitioning. However, there
is a practical issue of how to incorporate this change into the code.

It is straightforward if I simply change the partitionSieve() function
in the Partitioner.hh file.
But  I want to do this in my code (i.e. not changing the petsc-dev
code so that I don't have to patch it every time I update petsc-dev).
So we might need an interface to the petsc-dev library to take care of it.
Maybe a "User" partitioner needs to be created in parallel to "Chaco"
and "Parmetis" and  the assignment array can be supplied as a function
parameter?

Please let me know if this is possible and I would love to hear your
suggestions.
Thank you very much.
-- 

Sincerely,
Shi Jin, Ph.D.
http://www.ualberta.ca/~sjin1/
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