[petsc-users] DMPlex partition problem

[Matthew Knepley]

On Wed, Apr 8, 2020 at 12:48 AM Danyang Su <danyang.su at gmail.com> wrote:

> Dear All,
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> Hope you are safe and healthy.
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> I have a question regarding pretty different partition results of prism
> mesh. The partition in PETSc generates much more ghost nodes/cells than the
> partition in Gmsh, even though both use metis as partitioner. Attached
> please find the prism mesh in both vtk and exo format, the test code
> modified based on ex1f90 example. Similar problem are observed for larger
> dataset with more layers.
>

I will figure this out by next week.

  Thanks,

     Matt


> For example, in Gmsh, I get partition results using two processors and
> four processors as shown below, which are pretty reasonable.
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> However, in PETSc, the partition looks a bit weird. Looks like it takes
> layer partition first and then inside layer. If the number of nodes per
> layer is very large, this kind of partitioning results into much more ghost
> nodes/cells.
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> Anybody know how to improve the partitioning in PETSc? I have tried
> parmetis and chaco. There is no big difference between them.
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> Thanks,
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> Danyang
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>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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