Mark Adams <[email protected]> writes: > '-pc_gamg_verbose 2' will print out stuff where you can see the number of > active processors. We have not been super motivated to use subcoms because > there are no norms taken on coarse grids, except in the eigen estimator for > cheby, unless you use krylov in the solver, which is not usually useful. > Jed: GAMG does reduce active processors by default. I'm pretty sure.
Yup, it reduces the active process set, but does not create a subcomm, There are no reductions (inner products or norms) on the coarse grid in the current configuration. Iterative coarse solvers would be a good reason to create a subcomm.
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