[petsc-users] PCMG with shell restrictions

Matteo Semplice matteo.semplice at uninsubria.it
Tue Dec 10 10:20:16 CST 2024 

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!c1PFRpf9jqVzaF3p98Od2T92U1LOgy4Q3oqZCcYrv2QsIO885A3iP7Lo3XpDveKwS7CMeHxzVseroufdL1mP8nbei0E_jEnpPsLtNQ$  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> 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!c1PFRpf9jqVzaF3p98Od2T92U1LOgy4Q3oqZCcYrv2QsIO885A3iP7Lo3XpDveKwS7CMeHxzVseroufdL1mP8nbei0E_jEmoPycXyw$  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----------
>>
>> 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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20241210/f7a6a85c/attachment-0001.html>

More information about the petsc-users mailing list