[Trilinos-Users] Partitioning Tpetra matrices

[Pavel Jiránek]

Hello,

I was wondering what are the options for partitioning Tpetra matrices (no
geometry, pure graph partitioning) in Trilinos (in particular with long
integer global indices).

I've noticed that there might be some support for Tpetra through Isorropia
(although only for normal integers, I guess because Zoltan is hard-coded
with int types), however, Trilinos does not compile after using
Isorropia_ENABLE_TPETRA=ON in my config script.

I've also tried Zoltan2. I understand that, at this moment, the only option
for graph partitioning is through the interface to PT-Scotch (I suppose
working as well for long integers as soon as PT-Scotch is built with the
proper option for integer length). It seems to work well for improving
partitionings of already distributed matrices/graphs, however, the program
crashes (it seems that somewhere in the construction of a GraphModel
instance) on processes which do not contain any rows. For instance, this
happens when reading a (rather small) matrix on process 0 and computing a
partitioning from scratch. Interestingly, this problem can be fixed by
first naively redistributing the matrix to a uniform map and then applying
Zoltan2 to the redistributed matrix.

Thanks for any feedback.

Cheers,
Pavel
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