On 05.31.2012 15:58, Jed Brown wrote: > On Thu, May 31, 2012 at 3:47 PM, Jozsef Bakosi <jbakosi at lanl.gov> wrote: > > > I don't seem to find any additional output from -ksp_view. Am I doing > > something wrong when I simply pass -ksp_view to the exectuable? > > > > The full file would be 48M, here is a snippet that keeps coming from all > > cores: > > > > [44]PETSC ERROR: --------------------- Error Message > > ----------------------------------- > > [44]PETSC ERROR: Detected zero pivot in LU factorization see > > > > http://www.mcs.anl.gov/petsc/petsc-as/documentation/troubleshooting.html#ZeroPivot > > ! > > [44]PETSC ERROR: Zero pivot row 537 value 9.36276e-13 tolerance 1e-12! > > [44]PETSC ERROR: > > ------------------------------------------------------------------------ > > [44]PETSC ERROR: Petsc Release Version 3.1.0, Patch 8, Thu Mar 17 13:37:48 > > CDT 2011 > > [44]PETSC ERROR: See docs/changes/index.html for recent updates. > > [44]PETSC ERROR: See docs/faq.html for hints about trouble shooting. > > [44]PETSC ERROR: See docs/index.html for manual pages. > > [44]PETSC ERROR: > > ------------------------------------------------------------------------ > > [44]PETSC ERROR: Unknown Name on a conejo-gn named mu0455.localdomain by > > jbakosi Thu May 31 14:26:36 2012 > > [44]PETSC ERROR: Libraries linked from > > /scratch3/jbakosi/code/hydra/tpl/gnu/lib > > [44]PETSC ERROR: Configure run at Mon May 21 09:35:16 2012 > > [44]PETSC ERROR: Configure options PETSC_DIR=/tmp/temp/petsc-3.1-p8 > > PETSC_ARCH=conejo-gnu-opt --prefix=/scratch3/jbakosi/code/hydra/tpl/gnu > > --with-clanguage=c++ --with-x=false --with-x11=false > > --download-ml=/scratch3/jbakosi/code/hydra/tpl/tarballs/ml-6.2.tar.gz > > --with-debugging=0 -COPTFLAGS=-O3 -CXXOPTFLAGS=-O3 -FOPTFLAGS=-O3 > > -FFLAGS=-ffree-line-length-none > > [44]PETSC ERROR: > > ------------------------------------------------------------------------ > > [44]PETSC ERROR: MatLUFactorNumeric_SeqAIJ() line 574 in > > src/mat/impls/aij/seq/aijfact.c > > [44]PETSC ERROR: MatLUFactorNumeric() line 2587 in > > src/mat/interface/matrix.c > > [44]PETSC ERROR: PCSetUp_LU() line 158 in src/ksp/pc/impls/factor/lu/lu.c > > [44]PETSC ERROR: PCSetUp() line 795 in src/ksp/pc/interface/precon.c > > [44]PETSC ERROR: KSPSetUp() line 237 in src/ksp/ksp/interface/itfunc.c > > [44]PETSC ERROR: PCSetUp_Redundant() line 179 in > > src/ksp/pc/impls/redundant/redundant.c > > [44]PETSC ERROR: PCSetUp() line 795 in src/ksp/pc/interface/precon.c > > [44]PETSC ERROR: KSPSetUp() line 237 in src/ksp/ksp/interface/itfunc.c > > [44]PETSC ERROR: PCSetUp_MG() line 602 in src/ksp/pc/impls/mg/mg.c > > [44]PETSC ERROR: PCSetUp_ML() line 668 in src/ksp/pc/impls/ml/ml.c > > [44]PETSC ERROR: PCSetUp() line 795 in src/ksp/pc/interface/precon.c > > [44]PETSC ERROR: KSPSetUp() line 237 in src/ksp/ksp/interface/itfunc.c > > [44]PETSC ERROR: User provided function() line 275 in > > "unknowndirectory/"/scratch3/jbakosi/code/hydra/src/LinearAlgebra/PetscSolver.C > > > > These are the options you can use to control the shift (assuming you > haven't added your own prefix; you can check for yourself with -help) > > -mg_coarse_redundant_pc_factor_shift_type <NONE> (choose one of) NONE > NONZERO POSITIVE_DEFINITE INBLOCKS (PCFactorSetShiftType) > -mg_coarse_redundant_pc_factor_shift_amount <0>: Shift added to diagonal > (PCFactorSetShiftAmount) > -mg_coarse_redundant_pc_factor_zeropivot <2.22045e-14>: Pivot is > considered zero if less than (PCFactorSetZeroPivot) >
Great. Thanks. When I pass these options on the command line, how can I get a feedback to see if the option has actually been used or not? > > > What discretization are you using? > > > > Straightforward Galerkin FEM Poisson solver. > > > > What boundary conditions? I'm guessing the constant is in the null space, > in which case the coarse space really should be singular and you should not > be trying to solve it with a direct solver. I do set the additive constant. I have no problem with this on lower core-counts. I did another test and set the PETSC_OPTIONS environment variable to '-options_table -options_left', then I get: ... [49]PETSC ERROR: Zero pivot row 537 value 9.36276e-13 tolerance 1e-12! ... #PETSc Option Table entries: -mg_levels_ksp_norm_type no -mg_levels_ksp_richardson_scale 0.90 -mg_levels_ksp_type richardson -mg_levels_pc_type bjacobi -mg_levels_sub_ksp_norm_type no -mg_levels_sub_ksp_type preonly -mg_levels_sub_pc_type icc -options_left -options_table -pc_asm_overlap 1 -pc_mg_cycle_type v -pc_mg_smoothdown 1 -pc_mg_smoothup 1 -pc_ml_maxCoarseSize 1500 -pc_ml_maxNlevels 10 -pc_type asm -sub_pc_factor_levels 0 -sub_pc_factor_zeropivot 1e-20 -sub_pc_type ilu #End of PETSc Option Table entries There are no unused options. So how do I tell, which zeropivot setting (the 1e-20 or the 1e-12) is the one petsc is using? Thanks, J
