"Mark F. Adams" <[email protected]> writes: > run3.txt uses: > > -ksp_type richardson > > This is bad and I doubt anyone recommended it intentionally.
I would have expected FGMRES, but Barry likes Krylov smoothers and Richardson is one of a few methods that can tolerate nonlinear preconditioners. > You also have, in this file, > > -mg_levels_ksp_type gmres > > did you or the recommenders mean > > -mg_levels_ksp_type richardson ??? > > you are using gmres here, which forces you to use fgmres in the outer solver. > This is a safe thing to use you if you apply your BCa symmetrically with a > low order discretization then > > -ksp_type cg > -mg_levels_ksp_type richardson > -mg_levels_pc_type sor > > is what I'd recommend. I thought that was tried in an earlier round. I don't understand why SOR preconditioning in the Krylov smoother is so drastically more expensive than BJacobi/ILU and why SOR is called so many more times even though the number of outer iterations bjacobi: PCApply 322 1.0 4.1021e+01 1.0 6.44e+09 1.0 3.0e+07 1.6e+03 4.5e+04 74 86 98 88 92 28160064317351226 20106 bjacobi: KSPSolve 46 1.0 4.6268e+01 1.0 7.52e+09 1.0 3.0e+07 1.8e+03 4.8e+04 83100100 99 99 31670065158291309 20800 sor: PCApply 1132 1.0 1.5532e+02 1.0 2.30e+10 1.0 1.0e+08 1.6e+03 1.6e+05 69 88 99 88 93 21871774317301274 18987 sor: KSPSolve 201 1.0 1.7101e+02 1.0 2.63e+10 1.0 1.1e+08 1.8e+03 1.7e+05 75100100 99 98 24081775248221352 19652
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