[petsc-users] snes matrix-free jacobian fails with preconditioner shape mismatch

Sun Mar 10 07:55:01 CDT 2024

It looks like your input vector is the global vector, size 162, and
the local matrix size is 81.

Mark

[1]PETSC ERROR: Preconditioner number of local rows 81 does not equal
input vector size 162

On Sun, Mar 10, 2024 at 7:21 AM Yi Hu <y.hu at mpie.de> wrote:

> Dear petsc team, I implemented a matrix-free jacobian, and it can run
> sequentially. But running parallel I got the pc error like this (running
> with mpirun -np 2, only error from rank1 is presented here) [1]PETSC ERROR:
> ---------------------
> ZjQcmQRYFpfptBannerStart
> This Message Is From an External Sender
> This message came from outside your organization.
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> ZjQcmQRYFpfptBannerEnd
>
> Dear petsc team,
>
> I implemented a matrix-free jacobian, and it can run sequentially. But
> running parallel I got the pc error like this (running with mpirun -np
> 2, only error from rank1 is presented here)
>
> [1]PETSC ERROR: --------------------- Error Message
> --------------------------------------------------------------
> [1]PETSC ERROR: Nonconforming object sizes
> [1]PETSC ERROR: Preconditioner number of local rows 81 does not equal
> input vector size 162
> [1]PETSC ERROR: See https://urldefense.us/v3/__https://petsc.org/release/faq/__;!!G_uCfscf7eWS!ahmistzr4wD3TJ0OvI0JWxB9aVSIbP78Jcs2X_6KMb4LdoR8drLB_DkHvaguhrca22RgFer0PlyUrtdfCA$ for trouble shooting.
> [1]PETSC ERROR: Petsc Release Version 3.17.3, Jun 29, 2022
> [1]PETSC ERROR: /home/yi/workspace/DAMASK_yi/bin/DAMASK_grid on a
> arch-linux-c-opt named carbon-x1 by yi Sun Mar 10 12:01:46 2024
> [1]PETSC ERROR: Configure options --download-fftw --download-hdf5
> --with-hdf5-fortran-bindings --download-fblaslapack --download-chaco
> --download-hypre --download-metis --download-mumps --download-parmetis
> --download-scalapack --download-suitesparse --download-superlu
> --download-superlu_dist --download-triangle --download-zlib
> --download-cmake --with-cxx-dialect=C++11 --with-c2html=0
> --with-debugging=0 --with-ssl=0 --with-x=0 COPTFLAGS=-O3 CXXOPTFLAGS=-O3
> FOPTFLAGS=-O3
> [1]PETSC ERROR: #1 PCApply() at
> /home/yi/App/petsc-3.17.3/src/ksp/pc/interface/precon.c:424
> [1]PETSC ERROR: #2 KSP_PCApply() at
> /home/yi/App/petsc-3.17.3/include/petsc/private/kspimpl.h:376
> [1]PETSC ERROR: #3 KSPInitialResidual() at
> /home/yi/App/petsc-3.17.3/src/ksp/ksp/interface/itres.c:64
> [1]PETSC ERROR: #4 KSPSolve_GMRES() at
> /home/yi/App/petsc-3.17.3/src/ksp/ksp/impls/gmres/gmres.c:242
> [1]PETSC ERROR: #5 KSPSolve_Private() at
> /home/yi/App/petsc-3.17.3/src/ksp/ksp/interface/itfunc.c:902
> [1]PETSC ERROR: #6 KSPSolve() at
> /home/yi/App/petsc-3.17.3/src/ksp/ksp/interface/itfunc.c:1078
> [1]PETSC ERROR: #7 SNESSolve_NEWTONLS() at
> /home/yi/App/petsc-3.17.3/src/snes/impls/ls/ls.c:222
> [1]PETSC ERROR: #8 SNESSolve() at
> /home/yi/App/petsc-3.17.3/src/snes/interface/snes.c:4756
> [1]PETSC ERROR: #9 User provided function() at User file:0
>
> However, from snes matrix-free documentation
> (https://urldefense.us/v3/__https://petsc.org/release/manual/snes/*matrix-free-methods__;Iw!!G_uCfscf7eWS!ahmistzr4wD3TJ0OvI0JWxB9aVSIbP78Jcs2X_6KMb4LdoR8drLB_DkHvaguhrca22RgFer0Ply6ZbywOw$), it is said
> matrix-free is used with pcnone. So I assume it would not apply
> preconditioner, but it did use preconditioning probably the same as my
> matrix-free shell matrix. Here is how i initialize my shell matrix and
> the corresponding customized multiplication.
>
>    call MatCreateShell(PETSC_COMM_WORLD,PETSC_DECIDE,PETSC_DECIDE,&
> int(9*product(cells(1:2))*cells3,pPETSCINT),&
> int(9*product(cells(1:2))*cells3,pPETSCINT),&
>                        F_PETSc,Jac_PETSc,err_PETSc)
>    call MatShellSetOperation(Jac_PETSc,MATOP_MULT,GK_op,err_PETSc)
>    call SNESSetDM(SNES_mech,DM_mech,err_PETSc)
>    call
> SNESSetJacobian(SNES_mech,Jac_PETSc,Jac_PETSc,PETSC_NULL_FUNCTION,0,err_PETSc)
>    call SNESGetKSP(SNES_mech,ksp,err_PETSc)
>    call PCSetType(pc,PCNONE,err_PETSc)
>
> And my GK_op is like
>
> subroutine GK_op(Jac,dF_global,output_local,err_PETSc)
>
>    DM                                   :: dm_local
>    Vec                                  :: dF_global, dF_local, output_local
>    Mat                                  :: Jac
>    PetscErrorCode                       :: err_PETSc
>
>    real(pREAL), pointer,dimension(:,:,:,:) :: dF_scal, output_scal
>
>    real(pREAL), dimension(3,3,cells(1),cells(2),cells3) :: &
>      dF
>    real(pREAL), dimension(3,3,cells(1),cells(2),cells3) :: &
>      output
>
>    call SNESGetDM(SNES_mech,dm_local,err_PETSc)
>
>    call DMGetLocalVector(dm_local,dF_local,err_PETSc)
>    call
> DMGlobalToLocalBegin(dm_local,dF_global,INSERT_VALUES,dF_local,err_PETSc)
>    call
> DMGlobalToLocalEnd(dm_local,dF_global,INSERT_VALUES,dF_local,err_PETSc)
>
>    call DMDAVecGetArrayReadF90(dm_local,dF_local,dF_scal,err_PETSc)
>    dF = reshape(dF_scal, [3,3,cells(1),cells(2),cells3])
>
> .......
>
>
>    call DMDAVecRestoreArrayF90(dm_local,output_local,output_scal,err_PETSc)
>    CHKERRQ(err_PETSc)
>
>    call DMDAVecRestoreArrayF90(dm_local,dF_local,dF_scal,err_PETSc)
>    CHKERRQ(err_PETSc)
>
> end subroutine GK_op
>
> I checked my cells3, it corresponds to my local size, and it seems the
> local size of dF_local is ok.
>
> I am a bit lost here to find the reason for the preconditioner bug.
> Could you help me on this? Thanks.
>
> Best regards,
>
> Yi
>
>
>
>
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