[petsc-users] fieldsplit doesn't pass prefix to inner ksp

[Matthew Knepley]

On Fri, Sep 26, 2014 at 7:29 AM, anton <popov at uni-mainz.de> wrote:

> Create preconditioner:
>
> PCCreate(PETSC_COMM_WORLD, &pc);
> PCSetOptionsPrefix(pc, "bf_");
> PCSetFromOptions(pc);
>
> Define fieldsplit options:
>
> -bf_pc_type fieldsplit
> -bf_pc_fieldsplit_type SCHUR
> -bf_pc_fieldsplit_schur_factorization_type UPPER
>
> Works OK.
>
> Set options for the first field solver:
>
> -bf_fieldsplit_0_ksp_type preonly
> -bf_fieldsplit_0_pc_type lu
>
> Doesn't work (ignored), because "bf_" prefix isn't pass to inner solver
> ksp (checked in the debugger).
>
> Indeed, the following works:
>
> -fieldsplit_0_ksp_type preonly
> -fieldsplit_0_pc_type lu
>
> Observed with 3.5 but not with 3.4
>

I just tried this with master on SNES ex19, and got the correct result:

knepley/feature-parallel-partition
*$:/PETSc3/petsc/petsc-dev/src/snes/examples/tutorials$ ./ex19 -bf_pc_type
fieldsplit -bf_snes_view
./ex19 -bf_pc_type fieldsplit -bf_snes_view
lid velocity = 0.0625, prandtl # = 1, grashof # = 1
SNES Object:(bf_) 1 MPI processes
  type: newtonls
  maximum iterations=50, maximum function evaluations=10000
  tolerances: relative=1e-08, absolute=1e-50, solution=1e-08
  total number of linear solver iterations=13
  total number of function evaluations=3
  SNESLineSearch Object:  (bf_)   1 MPI processes
    type: bt
      interpolation: cubic
      alpha=1.000000e-04
    maxstep=1.000000e+08, minlambda=1.000000e-12
    tolerances: relative=1.000000e-08, absolute=1.000000e-15,
lambda=1.000000e-08
    maximum iterations=40
  KSP Object:  (bf_)   1 MPI processes
    type: gmres
      GMRES: restart=30, using Classical (unmodified) Gram-Schmidt
Orthogonalization with no iterative refinement
      GMRES: happy breakdown tolerance 1e-30
    maximum iterations=10000, initial guess is zero
    tolerances:  relative=1e-05, absolute=1e-50, divergence=10000
    left preconditioning
    using PRECONDITIONED norm type for convergence test
  PC Object:  (bf_)   1 MPI processes
    type: fieldsplit
      FieldSplit with MULTIPLICATIVE composition: total splits = 4
      Solver info for each split is in the following KSP objects:
      Split number 0 Defined by IS
      KSP Object:      (bf_fieldsplit_x_velocity_)       1 MPI processes
        type: preonly
        maximum iterations=10000, initial guess is zero
        tolerances:  relative=1e-05, absolute=1e-50, divergence=10000
        left preconditioning
        using NONE norm type for convergence test
      PC Object:      (bf_fieldsplit_x_velocity_)       1 MPI processes
        type: ilu
          ILU: out-of-place factorization
          0 levels of fill
          tolerance for zero pivot 2.22045e-14
          using diagonal shift on blocks to prevent zero pivot [INBLOCKS]
          matrix ordering: natural
          factor fill ratio given 1, needed 1
            Factored matrix follows:
              Mat Object:               1 MPI processes
                type: seqaij
                rows=16, cols=16
                package used to perform factorization: petsc
                total: nonzeros=64, allocated nonzeros=64
                total number of mallocs used during MatSetValues calls =0
                  not using I-node routines
        linear system matrix = precond matrix:
        Mat Object:        (bf_fieldsplit_x_velocity_)         1 MPI
processes
          type: seqaij
          rows=16, cols=16
          total: nonzeros=64, allocated nonzeros=64
          total number of mallocs used during MatSetValues calls =0
            not using I-node routines
      Split number 1 Defined by IS
      KSP Object:      (bf_fieldsplit_y_velocity_)       1 MPI processes
        type: preonly
        maximum iterations=10000, initial guess is zero
        tolerances:  relative=1e-05, absolute=1e-50, divergence=10000
        left preconditioning
        using NONE norm type for convergence test
      PC Object:      (bf_fieldsplit_y_velocity_)       1 MPI processes
        type: ilu
          ILU: out-of-place factorization
          0 levels of fill
          tolerance for zero pivot 2.22045e-14
          using diagonal shift on blocks to prevent zero pivot [INBLOCKS]
          matrix ordering: natural
          factor fill ratio given 1, needed 1
            Factored matrix follows:
              Mat Object:               1 MPI processes
                type: seqaij
                rows=16, cols=16
                package used to perform factorization: petsc
                total: nonzeros=64, allocated nonzeros=64
                total number of mallocs used during MatSetValues calls =0
                  not using I-node routines
        linear system matrix = precond matrix:
        Mat Object:        (bf_fieldsplit_y_velocity_)         1 MPI
processes
          type: seqaij
          rows=16, cols=16
          total: nonzeros=64, allocated nonzeros=64
          total number of mallocs used during MatSetValues calls =0
            not using I-node routines
      Split number 2 Defined by IS
      KSP Object:      (bf_fieldsplit_Omega_)       1 MPI processes
        type: preonly
        maximum iterations=10000, initial guess is zero
        tolerances:  relative=1e-05, absolute=1e-50, divergence=10000
        left preconditioning
        using NONE norm type for convergence test
      PC Object:      (bf_fieldsplit_Omega_)       1 MPI processes
        type: ilu
          ILU: out-of-place factorization
          0 levels of fill
          tolerance for zero pivot 2.22045e-14
          using diagonal shift on blocks to prevent zero pivot [INBLOCKS]
          matrix ordering: natural
          factor fill ratio given 1, needed 1
            Factored matrix follows:
              Mat Object:               1 MPI processes
                type: seqaij
                rows=16, cols=16
                package used to perform factorization: petsc
                total: nonzeros=64, allocated nonzeros=64
                total number of mallocs used during MatSetValues calls =0
                  not using I-node routines
        linear system matrix = precond matrix:
        Mat Object:        (bf_fieldsplit_Omega_)         1 MPI processes
          type: seqaij
          rows=16, cols=16
          total: nonzeros=64, allocated nonzeros=64
          total number of mallocs used during MatSetValues calls =0
            not using I-node routines
      Split number 3 Defined by IS
      KSP Object:      (bf_fieldsplit_temperature_)       1 MPI processes
        type: preonly
        maximum iterations=10000, initial guess is zero
        tolerances:  relative=1e-05, absolute=1e-50, divergence=10000
        left preconditioning
        using NONE norm type for convergence test
      PC Object:      (bf_fieldsplit_temperature_)       1 MPI processes
        type: ilu
          ILU: out-of-place factorization
          0 levels of fill
          tolerance for zero pivot 2.22045e-14
          using diagonal shift on blocks to prevent zero pivot [INBLOCKS]
          matrix ordering: natural
          factor fill ratio given 1, needed 1
            Factored matrix follows:
              Mat Object:               1 MPI processes
                type: seqaij
                rows=16, cols=16
                package used to perform factorization: petsc
                total: nonzeros=64, allocated nonzeros=64
                total number of mallocs used during MatSetValues calls =0
                  not using I-node routines
        linear system matrix = precond matrix:
        Mat Object:        (bf_fieldsplit_temperature_)         1 MPI
processes
          type: seqaij
          rows=16, cols=16
          total: nonzeros=64, allocated nonzeros=64
          total number of mallocs used during MatSetValues calls =0
            not using I-node routines
    linear system matrix = precond matrix:
    Mat Object:     1 MPI processes
      type: seqaij
      rows=64, cols=64, bs=4
      total: nonzeros=1024, allocated nonzeros=1024
      total number of mallocs used during MatSetValues calls =0
        using I-node routines: found 16 nodes, limit used is 5
Number of SNES iterations = 2

I will try with 3.5.2.

  Thanks,

    Matt


> Thanks.
> Anton
>



-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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