Than you Matt and Mark, I'll try your suggestions. To configure with hypre can I just use the --download-hypre configure line? That is what I did with suitesparse, very nice. ________________________________ From: Mark Adams <[email protected]> Sent: Monday, June 26, 2023 12:05 PM To: Vanella, Marcos (Fed) <[email protected]> Cc: [email protected] <[email protected]> Subject: Re: [petsc-users] SOLVE + PC combination for 7 point stencil (unstructured) poisson solution
I'm not sure what MG is doing with an "unstructured" problem. I assume you are not using DMDA. -pc_type gamg should work I would configure with hypre and try that also: -pc_type hypre As Matt said MG should be faster. How many iterations was it taking? Try a 100^3 and check that the iteration count does not change much, if at all. Mark On Mon, Jun 26, 2023 at 11:35 AM Vanella, Marcos (Fed) via petsc-users <[email protected]<mailto:[email protected]>> wrote: Hi, I was wondering if anyone has experience on what combinations are more efficient to solve a Poisson problem derived from a 7 point stencil on a single mesh (serial). I've been doing some tests of multigrid and cholesky on a 50^3 mesh. -pc_type mg takes about 75% more time than -pc_type cholesky -pc_factor_mat_solver_type cholmod for the case I'm testing. I'm new to PETSc so any suggestions are most welcome and appreciated, Marcos
