On Wed, Jan 14, 2009 at 20:04, jerome ho <jerome.snho at gmail.com> wrote: > boomeramg+minres: 388MB in 1min (8 iterations) > icc+cg: 165MB in 30min (>5000 iterations) > bjacobi+cg: 201MB in 50min (>5000 iterations)
Note that in serial, bjacobi is just whatever -sub_pc_type is (ilu by default). In parallel, it's always worth trying -pc_type asm as an alternative to bjacobi. You can frequently make the incomplete factorization stronger by using multiple levels (-pc_factor_levels N), but it will use more memory. It looks like multigrid works well for your problem so it will likely be very hard for a traditional method to compete. To reduce memory usage in BoomerAMG, try these options -pc_hypre_boomeramg_truncfactor <0>: Truncation factor for interpolation (0=no truncation) (None) -pc_hypre_boomeramg_P_max <0>: Max elements per row for interpolation operator ( 0=unlimited ) (None) -pc_hypre_boomeramg_agg_nl <0>: Number of levels of aggressive coarsening (None) -pc_hypre_boomeramg_agg_num_paths <1>: Number of paths for aggressive coarsening (None) -pc_hypre_boomeramg_strong_threshold <0.25>: Threshold for being strongly connected (None) For 3D problems, the manual suggests setting strong_threshold to 0.5. It's also worth trying ML, especially for vector problems. Jed
