[Trilinos-Users] need some help with Isorropia

Erik Boman egboman at sandia.gov
Fri Jul 11 09:06:28 MDT 2008


I think you should probably use Zoltan directly for this, not Isorropia.
since Isorropia only supports a subset of the functionality in Zoltan.
(Note that Zoltan currently is not in Trilinos but it will be a Trilinos
package in the upcoming 9.0 release.)

To satisfy your partitioning constraints I suggest you
(a) treat the six dof at each grid point as a single "data object" for
(b) give Zoltan a 2D problem (only x-y coordinates)

I suggest you first try the geometric partitioner RCB, which is fast and
often gives good results for meshes. If you need higher quality
partitions (with less communication) you can use the hypergraph
partitioner in Zoltan but the partitioning time will be higher. This may
not be a concern if you only partition once.

For more information on Zoltan, see http://www.cs.sandia.gov/Zoltan/
I recommend the slides from our tutorial as an introduction.


On Fri, 2008-07-11 at 05:47 -0600, Jonas Thies wrote:
> Hi all,
> I am trying to solve a load-balancing problem, can anyone give me some
> advice or pointer to further reading? I have no experience with Zoltan
> and the like, so maybe this is trivial.
> Here's the setting:
> I compute the Jacobian of a set of 6 coupled nonlinear PDE on a
> structured grid based on a simple 2D decomposition of the 3D rectangular
> domain where everyone has (roughly) the same subdomain size. Before
> solving the linear system, I would like to redistribute it based on
> vertex weights (which I determine from physical properties) and
> communication issues (minimal edge cut) under the constraints that
> (a) the six dof in each grid cell stay together
> (b) the z-direction shouldn't be split up (the decomposition should
> remain 2D but the domains needn't be rectangular in the x/y directions
> for the solve).
> thanks for your help,
> Jonas
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