[petsc-users] PCMG with shell restrictions

Tue Dec 10 09:38:08 CST 2024

   It appears you are completely ignoring the vec argument? Take a look at, for example, DMCreateInterpolation_DA() you will see you need to provide an appropriate vec in the same way you need (and do) provide an appropriate mat.

   Barry

> On Dec 10, 2024, at 7:02 AM, Matteo Semplice via petsc-users <petsc-users at mcs.anl.gov> wrote:
> 
> Dear petsc-users,
> 
>     I am trying with a student to modify the MG example 65 to use mat-shells instead of assembled matrices. Our use case is for a method that will use custom shell operators and shell interpolation/restrictions.
> 
> To start we have modified ex65 and tried to replace the standard restriction/interpolation with a shell matrix that performs the same operations on the DMDA grids.
> 
> I attach our modifications to ex65.
> 
> The problem is that the code sometimes completes execution and sometimes errors out like
> 
> $ ./ex65shell -ksp_monitor -pc_type mg -da_refine 2 -ksp_rtol 1e-1  
> >> Created DMshell 0x55bbc83c91a0 (0x55bbc8390a80) 
> Calling KSPSolve from main 
> computeRHS on grid 513 
> computeMatrix on grid 513 
> Inside Coarsen 
> >> Created DMshell 0x55bbc84c5270 (0x55bbc84b2ff0) 
> Inside Coarsen 
> >> Created DMshell 0x55bbc84e0a30 (0x55bbc84bdb60) 
> >> Create interpolation from 0x55bbc84c5270(0x55bbc84b2ff0) to 0x55bbc83c91a0(0x55bbc8390a80) 
> [0]PETSC ERROR: --------------------- Error Message -------------------------------------------------------------- 
> [0]PETSC ERROR: Invalid pointer 
> [0]PETSC ERROR: Invalid Pointer to PetscObject: Argument 'obj' (parameter # 1) 
> [0]PETSC ERROR: See https://urldefense.us/v3/__https://petsc.org/release/faq/__;!!G_uCfscf7eWS!ZLNRcAWCboFilZVAcU1gjUddxWbwjb25jRNK4CCZCz9YuJ22SpOf-bCIgcXbHcwhuzs4UiqEsjcnvKnre3OGa-c$  <https://urldefense.us/v3/__https://petsc.org/release/faq/__;!!G_uCfscf7eWS!Y29qRoOD71oxcd-BQFTUohkIToMJNW3puZ3CerpZ6pBnecqhBQ8TBwhSnikLt4BYQTmsBgtKvoCFi-JuLXQAE_Oe_a_d2XOL8KvOmw$> for trouble shooting. 
> [0]PETSC ERROR: Petsc Release Version 3.22.0, unknown  
> [0]PETSC ERROR: ./ex65shell with 1 MPI process(es) and PETSC_ARCH  on signalkuppe by matteo Tue Dec 10 12:55:12 2024 
> [0]PETSC ERROR: Configure options: --prefix=/home/matteo/software/petscsaved/3.22-opt/ PETSC_DIR=/home/matteo/software/petsc --PETSC_ARCH=dbg --with-debugging=1 --with-st
> rict-petscerrorcode --download-hdf5 --download-ml --with-metis --with-parmetis --with-gmsh --with-triangle --with-zlib --with-p4est-dir=~/software/p4est/local/ 
> [0]PETSC ERROR: #1 PetscObjectReference() at /home/matteo/software/petsc/src/sys/objects/inherit.c:620 
> [0]PETSC ERROR: #2 PCMGSetRScale() at /home/matteo/software/petsc/src/ksp/pc/impls/mg/mgfunc.c:394 
> [0]PETSC ERROR: #3 PCSetUp_MG() at /home/matteo/software/petsc/src/ksp/pc/impls/mg/mg.c:998 
> [0]PETSC ERROR: #4 PCSetUp() at /home/matteo/software/petsc/src/ksp/pc/interface/precon.c:1071 
> [0]PETSC ERROR: #5 KSPSetUp() at /home/matteo/software/petsc/src/ksp/ksp/interface/itfunc.c:415 
> [0]PETSC ERROR: #6 KSPSolve_Private() at /home/matteo/software/petsc/src/ksp/ksp/interface/itfunc.c:826 
> [0]PETSC ERROR: #7 KSPSolve() at /home/matteo/software/petsc/src/ksp/ksp/interface/itfunc.c:1075 
> [0]PETSC ERROR: #8 main() at ../src/ex65shell.c:79 
> [0]PETSC ERROR: PETSc Option Table entries: 
> [0]PETSC ERROR: -da_refine 2 (source: command line) 
> [0]PETSC ERROR: -ksp_monitor (source: command line) 
> [0]PETSC ERROR: -ksp_rtol 1e-1 (source: command line) 
> [0]PETSC ERROR: -pc_type mg (source: command line) 
> [0]PETSC ERROR: ----------------End of Error Message -------send entire error message to petsc-maint at mcs.anl.gov <mailto:petsc-maint at mcs.anl.gov>----------
> 
> In all cases valgrind complains like
> 
> $ valgrind ./ex65shell -ksp_monitor -pc_type mg -da_refine 2 -ksp_rtol 1e-1 -int_view ascii::ascii_info 
> ==2130767== Memcheck, a memory error detector 
> ==2130767== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al. 
> ==2130767== Using Valgrind-3.19.0 and LibVEX; rerun with -h for copyright info 
> ==2130767== Command: ./ex65shell -ksp_monitor -pc_type mg -da_refine 2 -ksp_rtol 1e-1 -int_view ascii::ascii_info 
> ==2130767==  
> hwloc x86 backend cannot work under Valgrind, disabling. 
> May be reenabled by dumping CPUIDs with hwloc-gather-cpuid 
> and reloading them under Valgrind with HWLOC_CPUID_PATH. 
> >> Created DMshell 0xfbf50f0 (0xfb49480) 
> Calling KSPSolve from main 
> computeRHS on grid 513 
> computeMatrix on grid 513 
> Inside Coarsen 
> >> Created DMshell 0xff404a0 (0xff062d0) 
> Inside Coarsen 
> >> Created DMshell 0xff78ca0 (0xff4a530) 
> >> Create interpolation from 0xff404a0(0xff062d0) to 0xfbf50f0(0xfb49480) 
> Mat Object: 1 MPI process 
>  type: shell 
>  rows=513, cols=257 
> ==2130767== Conditional jump or move depends on uninitialised value(s) 
> ==2130767==    at 0x83FDAAE: PCSetUp_MG (mg.c:998) 
> ==2130767==    by 0x8620C04: PCSetUp (precon.c:1071) 
> ==2130767==    by 0x7DA78D5: KSPSetUp (itfunc.c:415) 
> ==2130767==    by 0x7DB2093: KSPSolve_Private (itfunc.c:826) 
> ==2130767==    by 0x7DB7A53: KSPSolve (itfunc.c:1075) 
> ==2130767==    by 0x10D2F7: main (ex65shell.c:79) 
> ==2130767==  
> ==2130767== Conditional jump or move depends on uninitialised value(s) 
> ==2130767==    at 0x5794061: VecDestroy (vector.c:570) 
> ==2130767==    by 0x83FDC36: PCSetUp_MG (mg.c:999) 
> ==2130767==    by 0x8620C04: PCSetUp (precon.c:1071) 
> ==2130767==    by 0x7DA78D5: KSPSetUp (itfunc.c:415) 
> ==2130767==    by 0x7DB2093: KSPSolve_Private (itfunc.c:826) 
> ==2130767==    by 0x7DB7A53: KSPSolve (itfunc.c:1075) 
> ==2130767==    by 0x10D2F7: main (ex65shell.c:79) 
> ==2130767==
> 
> We are clearly doing something wrong since PCSetUp_MG (mg.c:998)  is an area of code where I wouldn't expect we would enter.
> 
> Can you advise on the proper way to achieve our goal?
> 
> Best regards
> 
>     Matteo
> 
> <ex65.patch>

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