[petsc-users] PCMG with shell restrictions
Barry Smith
bsmith at petsc.dev
Tue Dec 10 10:27:22 CST 2024
Beats me :-) Just set it to whatever the DMDA sets it too
Barry
> On Dec 10, 2024, at 11:20 AM, Matteo Semplice <matteo.semplice at uninsubria.it> wrote:
>
> Thanks, Barry.
>
> Just to be sure, one should refer to the help of https://urldefense.us/v3/__https://petsc.org/release/manualpages/DM/DMCreateInterpolationScale/__;!!G_uCfscf7eWS!adeZHH1r8zFo3A5H1wpZDveIiI1ryL_lOJwl2MsOC0uuANOMda4SvkEHBjoh9sZgxTrk1G2RbGRejVvgyba9OYQ$ and the vec should be set to the point-wise inverse of (INTERPOLATION)*(vector of ones) ?
>
> Matteo
>
> On 10/12/2024 16:38, Barry Smith wrote:
>>
>> 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> <mailto: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!adeZHH1r8zFo3A5H1wpZDveIiI1ryL_lOJwl2MsOC0uuANOMda4SvkEHBjoh9sZgxTrk1G2RbGRejVvgZJWXKXM$ <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>
>>
> --
> Prof. Matteo Semplice
> Università degli Studi dell’Insubria
> Dipartimento di Scienza e Alta Tecnologia – DiSAT
> Professore Associato
> Via Valleggio, 11 – 22100 Como (CO) – Italia
> tel.: +39 031 2386316
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