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

Yi Hu y.hu at mpie.de
Sun Mar 10 09:16:15 CDT 2024


Dear Mark,

Thanks for your reply. I see this mismatch. In fact my global DoF is 
324. It seems like I always get the local size = global Dof / np^2, np 
is my processor number. By the way, I used DMDASNESsetFunctionLocal() to 
set my form function. Is it eligible to mix DMDASNESsetFunctionLocal() 
and a native SNESSetJacobian()?

Best,

Yi

On 3/10/24 13:55, Mark Adams wrote:
> 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.
>     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: Seehttps://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 Userfile: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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Amtsgericht Düsseldorf
 
Geschäftsführung
Prof. Dr. Gerhard Dehm
Prof. Dr. Jörg Neugebauer
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Dr. Kai de Weldige
 
Ust.-Id.-Nr.: DE 11 93 58 514 
Steuernummer: 105 5891 1000


Please consider that invitations and e-mails of our institute are 
only valid if they end with …@mpie.de. 
If you are not sure of the validity please contact rco at mpie.de

Bitte beachten Sie, dass Einladungen zu Veranstaltungen und E-Mails
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In Zweifelsfällen wenden Sie sich bitte an rco at mpie.de
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