On Tue, Jun 18, 2013 at 12:58 PM, Jens Lohne Eftang <[email protected]> wrote: > > On 06/18/2013 02:45 PM, John Peterson wrote: > > > > > On Tue, Jun 18, 2013 at 12:41 PM, Jens Lohne Eftang <[email protected]> wrote: >> >> Hi all, >> >> >> I'm solving a large 3D linear elasticity (steady) problem. My mesh has >> 8.8million nodes, so since this is a vector-valued problem there's >> around 26 million unknowns. >> >> The code is basically systems_of_equations_ex6 (except for the mesh >> generation part, and I also do not compute stresses). >> >> I have configured petsc with --download-ml, and I am running my program with >> >> mpirun -np 20 ./elasticity-opt -ksp_type cg -pc_type gamg >> -pc_gamg_agg_nsmooths 1 -ksp_monitor -ksp_converged_reason -log_summary >> >> that is, CG as the iterative solver and AMG as preconditioner. >> >> The problem is the huge amount of memory that this solve requires --- I >> have 128Gb memory, and I run out! Due to the large problem size I was of >> course expecting significant memory consumption, but not this bad. I did >> try ParallelMesh, but that did not change things. >> >> Am I doing something obviously wrong here? > > > Do you still run out of memory if you run without GAMG? > > There could be some GAMG options that control memory consumption, I don't know too much about it. > > I am able to to solve the problem with -pc_type bjacobi and -sub_pc_type icc, but that still uses a lot of memory, around 60Gb. And also this required more than 5000 CG iterations which is why I moved to AMG.
OK, switching from bjacobi -> GAMG caused memory consumption to more than double?! I'd definitely look into the GAMG options... Another possibility is that you could build PETSc with Hypre and run with: -pc_type hypre -pc_hypre_type boomeramg -pc_hypre_boomeramg_strong_threshold 0.7 -- John ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
