On Tue, Mar 28, 2023 at 12:38 PM Blaise Bourdin <bour...@mcmaster.ca> wrote:
> > > On Mar 27, 2023, at 9:11 PM, Mark Adams <mfad...@lbl.gov> wrote: > > Yes, the eigen estimates are converging slowly. > > BTW, have you tried hypre? It is a good solver (lots lots more woman years) > These eigen estimates are conceptually simple, but they can lead to > problems like this (hypre and an eigen estimate free smoother). > > I just moved from petsc 3.3 to main, so my experience with an old version > of hyper has not been very convincing. Strangely enough, ML has always been > the most efficient PC for me. > ML is a good solver. > Maybe it’s time to revisit. > That said, I would really like to get decent performances out of gamg. One > day, I’d like to be able to account for the special structure of > phase-field fracture in the construction of the coarse space. > > > But try this (good to have options anyway): > > -pc_gamg_esteig_ksp_max_it 20 > > Chevy will scale the estimate that we give by, I think, 5% by default. > Maybe 10. > You can set that with: > > -mg_levels_ksp_chebyshev_esteig 0,0.2,0,*1.05* > > 0.2 is the scaling of the high eigen estimate for the low eigen value in > Chebyshev. > > > > Jed’s suggestion of using -pc_gamg_reuse_interpolation 0 worked. > OK, have to admit I am surprised. But I guess with your fracture the matrix/physics/dynamics does change a lot > I am testing your options at the moment. > There are a lot of options and it is cumbersome but they are finite and good to know. Glad its working, > > Thanks a lot, > > Blaise > > — > Canada Research Chair in Mathematical and Computational Aspects of Solid > Mechanics (Tier 1) > Professor, Department of Mathematics & Statistics > Hamilton Hall room 409A, McMaster University > 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada > https://www.math.mcmaster.ca/bourdin | +1 (905) 525 9140 ext. 27243 > >
