[petsc-users] fieldsplit recursive

Fri Jun 29 11:35:48 CDT 2012

On Fri, Jun 29, 2012 at 12:17 AM, Kaus, Boris <kaus at uni-mainz.de> wrote:

> Hi,
>
> If I understand this correctly, it also implies that the
> fieldsplit-in-fieldsplit options described in Jed's manuscript on the new
> multiphysics options of PETSc
>
> http://www.mcs.anl.gov/uploads/cels/papers/P2017-0112.pdf
>
> section IV are broken in PETSC 3.3.
> That's a bummer as it is the preconditioner we most commonly used.
>

There are nightly tests that use these options
(src/ksp/ksp/examples/tests/ex11.c and
src/ksp/ksp/examples/tutorials/ex43.c) so it appears that this problem is
not always triggered. Thanks for the test case, we'll get this sorted out.

>
> cheers,
> Boris
>
>
>
>
>
>
> On Jun 28, 2012, at 8:55 PM, Barry Smith wrote:
>
> >  Anton,
> >
> >   This came about because we are now being much more pedantic about the
> blocksizes of PETSc objects and not allowing them to be causally changed
> when they shouldn't be.
> >
> >   You can resolve this problem by editing the file
> src/ksp/pc/impls/fieldsplit/fieldsplit.c locate the function
> >
> > #undef __FUNCT__
> > #define __FUNCT__ "PCApply_FieldSplit"
> > static PetscErrorCode PCApply_FieldSplit(PC pc,Vec x,Vec y)
> > {
> >  PC_FieldSplit     *jac = (PC_FieldSplit*)pc->data;
> >  PetscErrorCode    ierr;
> >  PC_FieldSplitLink ilink = jac->head;
> >  PetscInt          cnt,bs;
> >
> >  PetscFunctionBegin;
> >
> > and add the two lines right here
> >
> >  x->map->bs = jac->bs;
> >  y->map->bs = jac->bs;
> >
> >
> > then run make cmake in that directory.
> >
> > To resolve this permanently we will need to figure out how to insure
> those inner vectors are created with the correct block size. Are you
> willing to share your code with petsc-maint at mcs.anl.gov so that we can
> reproduce the problem and fix it properly for the long run? (The problem is
> in PETSc not in your code).
> >
> >   Barry
> >
> >
> >
> > On Jun 28, 2012, at 10:44 AM, Anton Popov wrote:
> >
> >> Dear petsc team,
> >>
> >> I'm trying to use fieldsplit preconditioner for the velocity block in
> the Stokes system which is also preconditioned by
> >> fieldsplit (kind of recursive).
> >>
> >> Running example 42 from src/ksp/ksp/examples/tutorials with petsc-3.2,
> as follows:
> >>
> >> mpiexec -np 4 ./ex42 \
> >> -stokes_ksp_type gcr \
> >> -stokes_ksp_rtol 1.0e-6 \
> >> -stokes_pc_type fieldsplit \
> >> -stokes_pc_fieldsplit_type SCHUR \
> >> -stokes_pc_fieldsplit_schur_factorization_type UPPER \
> >> -stokes_fieldsplit_u_ksp_type fgmres \
> >> -stokes_fieldsplit_u_ksp_rtol 1e-3 \
> >> -stokes_fieldsplit_u_pc_type fieldsplit \
> >> -stokes_fieldsplit_u_fieldsplit_ksp_type preonly \
> >> -stokes_fieldsplit_u_fieldsplit_pc_type ml \
> >> -stokes_fieldsplit_u_pc_fieldsplit_block_size 3 \
> >> -stokes_fieldsplit_u_pc_fieldsplit_type ADDITIVE \
> >> -stokes_fieldsplit_p_ksp_type preonly \
> >> -stokes_fieldsplit_p_pc_type jacobi \
> >> -stokes_ksp_monitor_blocks \
> >> -mx 16 \
> >> -model 3
> >>
> >> gives nicely looking output.
> >>
> >> But! Repeating the same exercise with petsc-3.3, like this (actually,
> there is only one difference: factorization -> fact):
> >>
> >> mpiexec -np 4 ./ex42 \
> >> -stokes_ksp_type gcr \
> >> -stokes_ksp_rtol 1.0e-6 \
> >> -stokes_pc_type fieldsplit \
> >> -stokes_pc_fieldsplit_type SCHUR \
> >> -stokes-pc_fieldsplit_schur_fact_type UPPER \
> >> -stokes_fieldsplit_u_ksp_type fgmres \
> >> -stokes_fieldsplit_u_ksp_rtol 1e-3 \
> >> -stokes_fieldsplit_u_pc_type fieldsplit \
> >> -stokes_fieldsplit_u_fieldsplit_ksp_type preonly \
> >> -stokes_fieldsplit_u_fieldsplit_pc_type ml \
> >> -stokes_fieldsplit_u_pc_fieldsplit_block_size 3 \
> >> -stokes_fieldsplit_u_pc_fieldsplit_type ADDITIVE \
> >> -stokes_fieldsplit_p_ksp_type preonly \
> >> -stokes_fieldsplit_p_pc_type jacobi \
> >> -stokes_ksp_monitor_blocks \
> >> -mx 16 \
> >> -model 3
> >>
> >> curses me hardly by claiming:
> >>
> >> [0]PETSC ERROR: --------------------- Error Message
> ------------------------------------
> >> [0]PETSC ERROR: Object is in wrong state!
> >> [0]PETSC ERROR: Blocksize of x vector 1 does not match fieldsplit
> blocksize 3!
> >> [0]PETSC ERROR:
> ------------------------------------------------------------------------
> >> [0]PETSC ERROR: Petsc Release Version 3.3.0, Patch 0, Tue Jun  5
> 14:20:42 CDT 2012
> >> [0]PETSC ERROR: See docs/changes/index.html for recent updates.
> >> [0]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
> >> [0]PETSC ERROR: See docs/index.html for manual pages.
> >> [0]PETSC ERROR:
> ------------------------------------------------------------------------
> >> [0]PETSC ERROR: ./ex42 on a int32-deb named mac11-005.geo.uni-mainz.deby anton Thu Jun 28 17:06:53 2012
> >> [0]PETSC ERROR: Libraries linked from
> /Users/anton/LIB/petsc-3.3-p0/int32-debug/lib
> >> [0]PETSC ERROR: Configure run at Tue Jun 12 15:32:21 2012
> >> [0]PETSC ERROR: Configure options
> PETSC_DIR=/Users/anton/LIB/petsc-3.3-p0 PETSC_ARCH=int32-debug
> --download-f-blas-lapack=1 --with-debugging=1 --COPTFLAGS="-g -O0"
> --FOPTFLAGS="-g -O0" --CXXOPTFLAGS="-g -O0" --with-c++-support=1
> --with-fortran=1 --with-fortran-kernels=1 --with-large-file-io=1
> --with-mpi-compilers=1 --with-cc=mpicc --with-cxx=mpicxx --with-fc=mpif90
> --download-ml=1 --download-hypre=1 --download-blacs=1
> --download-scalapack=1 --download-metis=1 --download-parmetis=1
> --download-mumps=1 --download-superlu_dist=1
> >> [0]PETSC ERROR:
> ------------------------------------------------------------------------
> >> [0]PETSC ERROR: PCApply_FieldSplit() line 726 in
> /Users/anton/LIB/petsc-3.3-p0/src/ksp/pc/impls/fieldsplit/fieldsplit.c
> >> [0]PETSC ERROR: PCApply() line 384 in
> /Users/anton/LIB/petsc-3.3-p0/src/ksp/pc/interface/precon.c
> >> [0]PETSC ERROR: KSPFGMRESCycle() line 169 in
> /Users/anton/LIB/petsc-3.3-p0/src/ksp/ksp/impls/gmres/fgmres/fgmres.c
> >> [0]PETSC ERROR: KSPSolve_FGMRES() line 294 in
> /Users/anton/LIB/petsc-3.3-p0/src/ksp/ksp/impls/gmres/fgmres/fgmres.c
> >> [0]PETSC ERROR: KSPSolve() line 446 in
> /Users/anton/LIB/petsc-3.3-p0/src/ksp/ksp/interface/itfunc.c
> >> [0]PETSC ERROR: PCApply_FieldSplit_Schur() line 693 in
> /Users/anton/LIB/petsc-3.3-p0/src/ksp/pc/impls/fieldsplit/fieldsplit.c
> >> [0]PETSC ERROR: PCApply() line 384 in
> /Users/anton/LIB/petsc-3.3-p0/src/ksp/pc/interface/precon.c
> >> [0]PETSC ERROR: KSPSolve_GCR_cycle() line 47 in
> /Users/anton/LIB/petsc-3.3-p0/src/ksp/ksp/impls/gcr/gcr.c
> >> [0]PETSC ERROR: KSPSolve_GCR() line 117 in
> /Users/anton/LIB/petsc-3.3-p0/src/ksp/ksp/impls/gcr/gcr.c
> >> [0]PETSC ERROR: KSPSolve() line 446 in
> /Users/anton/LIB/petsc-3.3-p0/src/ksp/ksp/interface/itfunc.c
> >> [0]PETSC ERROR: solve_stokes_3d_coupled() line 2045 in
> src/ksp/ksp/examples/tutorials/ex42.c
> >> [0]PETSC ERROR: main() line 2106 in
> src/ksp/ksp/examples/tutorials/ex42.c
> >> application called MPI_Abort(MPI_COMM_WORLD, 1) - process 0
> >>
> >> Similar error appeared in our code after upgrading to petsc-3.3, and
> we're using similar functionality and options as I posted above.
> >>
> >> Please explain this issue. An advice how to get rid of the error is
> also appreciated.
> >>
> >> Thanks a lot
> >>
> >> Anton
> >
>
>
>
>
> -----------------------------------------------------------------------------
> Boris J.P. Kaus
>
> Institute of Geosciences &
> Center for Computational Sciences.
> University of Mainz, Mainz, Germany
> Office:         00-285
> Tel:            +49.6131.392.4527
>
> http://www.geophysik.uni-mainz.de
>
> -----------------------------------------------------------------------------
>
>
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