[petsc-users] multigrid_repartitioning

[Mark F. Adams]

On Jan 27, 2012, at 12:18 PM, Jed Brown wrote:

> On Fri, Jan 27, 2012 at 11:16, Anton Popov <popov at uni-mainz.de> wrote:
> Does PETSc support repartitioning of coarse grid operators onto a smaller subset of processors during coarsening? Or the coarsest grid must be represented on the same amount of processors as the finest? It becomes a problem when a lot of processors are employed (say 4096 or more). If it is supported, how can I use it?
> 
> PCGAMG does this automatically. There are some technical challenges to doing this with geometric multigrid, but we are thinking about how to do it best.

GAMG does not repartition by default anymore -- it is very expensive.  GAMG does now do simple process aggregation on coarser grids if repartitioning is not specified.
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