> I do not understand this behavior : since MUMPS is a parallel direct solver, > shouldn't the solver converge in max 3 iterations whatever the number of > procs?
Please add the following options -fieldsplit_0_ksp_type gmres -fieldsplit_0_ksp_pc_side right -fieldsplit_0_ksp_monitor -fieldsplit_1_ksp_type gmres -fieldsplit_1_ksp_pc_side right -fieldsplit_1_ksp_monitor and send the output (don't bother with the -log_summary). Barry > On Jan 4, 2017, at 3:39 PM, Karin&NiKo <[email protected]> wrote: > > Dear Petsc team, > > I am (still) trying to solve Biot's poroelasticity problem : > <image.png> > > I am using a mixed P2-P1 finite element discretization. The matrix of the > discretized system in binary format is attached to this email. > > I am using the fieldsplit framework to solve the linear system. Since I am > facing some troubles, I have decided to go back to simple things. Here are > the options I am using : > > -ksp_rtol 1.0e-5 > -ksp_type fgmres > -pc_type fieldsplit > -pc_fieldsplit_schur_factorization_type full > -pc_fieldsplit_type schur > -pc_fieldsplit_schur_precondition selfp > -fieldsplit_0_pc_type lu > -fieldsplit_0_pc_factor_mat_solver_package mumps > -fieldsplit_0_ksp_type preonly > -fieldsplit_0_ksp_converged_reason > -fieldsplit_1_pc_type lu > -fieldsplit_1_pc_factor_mat_solver_package mumps > -fieldsplit_1_ksp_type preonly > -fieldsplit_1_ksp_converged_reason > > On a single proc, everything runs fine : the solver converges in 3 > iterations, according to the theory (see Run-1-proc.txt [contains -log_view]). > > On 2 procs, the solver converges in 28 iterations (see Run-2-proc.txt). > > On 3 procs, the solver converges in 91 iterations (see Run-3-proc.txt). > > I do not understand this behavior : since MUMPS is a parallel direct solver, > shouldn't the solver converge in max 3 iterations whatever the number of > procs? > > > Thanks for your precious help, > Nicolas > > <Run-1-proc.txt><Run-2-proc.txt><Run-3-proc.txt><1_Warning.txt>
