In talking with Garth, this will not work. I/we am now thinking that we should replace the MG object with Telescope. Telescope seems to be designed to be a superset of MG. Telescope does the processor reduction, and GAMG does as well, so we would have to reconcile this. Does this sound like a good idea? Am I missing anything important?
Mark On Tue, Jun 27, 2017 at 4:48 AM, Mark Adams <[email protected]> wrote: > Parallel coarse grid solvers are a bit broken at large scale where you > don't want to use all processors on the coarse grid. The ideal thing might > be to create a sub communicator, but it's not clear how to integrate this > in (eg, check if the sub communicator exists before calling the coarse grid > solver and convert if necessary). A bit messy. It would be nice if a > parallel direct solver would not redistribute the matrix, but then it would > be asking too much for it to reorder also, so we could have a crappy > ordering. So maybe the first option would be best long term. > > I see we have MUMPS and PaStiX. Do either of these not redistribute if > asked? >
