[petsc-users] Load balancing / redistributing a 1D DM

[Matthew Knepley]

On Mon, Mar 5, 2018 at 9:01 AM, Tobin Isaac <tisaac at cc.gatech.edu> wrote:

> This is a somewhat incomplete description of the steps in linear
> partitioning.  The rest can be accomplished with PetscSF calls, but I
> should wrap it up in a PetscPartitioner because it's a mistake-prone
> operation.
>

Jed likes to do everything by hand because it is transparent, but then you
become the maintainer.
I think this is easy to do in Plex, and we maintain the code. It is less
transparent, which is the tradeoff.

   Matt


> On March 5, 2018 8:31:42 AM EST, Jed Brown <jed at jedbrown.org> wrote:
> >Dave May <dave.mayhem23 at gmail.com> writes:
> >
> >> For a 1D problem such as yours, I would use your favourite graph
> >> partitioner (Metis,Parmetis, Scotch) together with your cell based
> >> weighting and repartition the data yourself.
> >
> >That's overkill in 1D.  You can MPI_Allreduce(SUM) and MPI_Scan(SUM)
> >the
> >weights, then find the transition indices in each subdomain.  It'll be
> >cheaper, more intuitive/deterministic, and avoid the extra library
> >dependency.  Of course if you think you may want to move to multiple
> >dimensions, it would make sense to consider DMPlex or DMForest.
>



-- 
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.caam.rice.edu/~mk51/>
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