[MOAB-dev] Interface: Partitioner

[Tim Tautges]

On 09/25/2013 07:15 AM, Alexander Nikolas Breuer wrote:
> Hey Tim,
>
> A short heads up: I'll have to postpone the work regarding the meshes a bit (December). Let me comment on the remarks
> anyhow:
>
>> Depends on what you're looking for.  mbpart is our tool to generate partitions, but it works for static
>> partitioning; we don't really do dynamic partitioning at the moment.  mbpart can establish the graph, which it
>> passes to Zoltan to do the actual partitioning.
>
> Static in the sense of AMR? Our mesh doesn't change over time -> If mbpart can create a graph from moabs underlying
> data management, we should be good to go and get some hints from the implementation of mbpart.

Static in the sense of using the same partition throughout the simulation (really it's about not doing migration to a 
new partition on the fly).

>
>> Zoltan in theory can use metis to generate the partition, though I haven't had much luck with it that way (though
>> maybe Zoltan2, which we haven't updated to, works better) (though now that I say that, it could just as easily be a
>> bug in moab which we haven't found).
>
> Ok, it's probably worth trying out Zoltan2 then, which supports arbitrary large meshes additionally (according to the
> homepage).
>
>> So, you could take the code from mbpart that generates the graph and passes to parmetis, and that would give you
>> back a partition.  You'd just need to make sure to establish shared mesh between processors correctly before doing
>> that (and possibly exchanging a row of ghost elements), to make sure that both processors sharing vertices would
>> see the same connected elements.  The HelloParMOAB example
>> (http://www.mcs.anl.gov/~fathom/moab-docs/html/HelloParMOAB_8cpp-example.html) shows how to request ghosting, after
>> you've established shared entities.
>
> Yah, I'll do that. Doing it in parallel was on of the main reasons for MOAB and on my schedule anyway. :)
>

Let me know how it works.  Since we use it as a serial tool, it may not work properly in parallel (I just checked, and 
there are multiple places that check for rank 0 that look a bit suspicious to me).

- tim

> Thanks for your reply & Regards,
>
> Alex
>

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              Tim Tautges            Argonne National Laboratory
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