[petsc-dev] GAMG key not found in table

[Pierre Jolivet]

> On 24 Jun 2018, at 6:15 PM, Mark Adams <mfadams at lbl.gov> wrote:
> 
> First, -pc_gamg_threshold 0.8  is crazy. 0.08 is very high. probably best to start with 0.

I know it’s high, but that is what works for my application (otherwise the setup takes forever for just one or two iterations less).
The problem is related to my previous email from Friday ([petsc-dev] GAMG and custom MatMults in smoothers, thanks Barry for the thorough answer), I basically need only two or three levels (extremely aggressive coarsening).

I don’t know if this can help, but depending on the value I use for the threshold, I also get this error:
ksp/pc/impls/gamg/agg.c:          if (flid < 0) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Cannot find gid1 in table”);

Of course, if I switch to an even crazier threshold, e.g., 0.999999, and end-up with a one-level method, I don’t see such an error.

I know I am to blame here but my application does not use PetscInt as default integers (plain int instead). I use a lot of MatMPIAIJSetPreallocationCSR, so it is not as easy as simply recompiling with --with-64-bit-indices for me.
I’d gladly try anything that you suggest which would still use 32 bit indices as "primary PetscInt type".

Thanks,
Pierre

> This threshold will delete all of your edges in the coarsening graph, probably, and GAMG will switch to a one level solve (silently although -info will tell you).
> 
> And yes, this looks like a 64 bit indices problem, we have:
> 
> #define GAMG_HASH(key) ((((PetscInt)7)*key)%a_tab->size)
> 
> We should probably cast everything to (long long) or (unsigned PetscInt) I guess ... I'm not sure how this should be done exactly.  Any ideas from the peanut gallery?
> 
> 
> 
> On Sun, Jun 24, 2018 at 2:34 AM Pierre Jolivet <pierre.jolivet at enseeiht.fr <mailto:pierre.jolivet at enseeiht.fr>> wrote:
> Hello,
> Any ideas on how to debug this?
> [406]PETSC ERROR: key 328214936 not found in table
> [406]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html <http://www.mcs.anl.gov/petsc/documentation/faq.html> for trouble shooting.
> [406]PETSC ERROR: Petsc Development GIT revision: v3.9.2-603-gceafe64  GIT Date: 2018-06-10 12:46:16 -0500
> [406]PETSC ERROR: /ccc/work/cont003/rndm/rndm/FreeFem-sources/src/mpi/FreeFem++-mpi on a arch-linux2-c-debug-bullxmpi named curie2698 by jolivetp Sun Jun 24 07:06:07 2018
> [406]PETSC ERROR: Configure options --with-scalar-type=real --with-hypre-dir=arch-linux2-c-opt-bullxmpi --with-metis-dir=arch-linux2-c-opt-bullxmpi --with-mumps-dir=arch-linux2-c-opt-bullxmpi --with-mkl_cpardiso=1 --with-mkl_pardiso=1 --with-parmetis-dir=arch-linux2-c-opt-bullxmpi --with-ptscotch-dir=arch-linux2-c-opt-bullxmpi --with-sowing-dir=arch-linux2-c-opt-bullxmpi --with-blacs-include=/ccc/products/mkl-18.0.1.163/default/18.0.1.163/mkl/include <http://18.0.1.163/mkl/include> --with-blacs-lib=/ccc/products/mkl-18.0.1.163/default/18.0.1.163/mkl/lib/intel64/libmkl_blacs_openmpi_lp64.so <http://18.0.1.163/mkl/lib/intel64/libmkl_blacs_openmpi_lp64.so> --with-blaslapack-dir=/ccc/products/mkl-18.0.1.163/default/18.0.1.163/mkl/lib/intel64 <http://18.0.1.163/mkl/lib/intel64> --with-x=0 --with-debugging=1 --with-errorchecking=1 --with-mkl_pardiso-dir=/ccc/products/mkl-18.0.1.163/default/18.0.1.163/mkl <http://18.0.1.163/mkl> --with-mkl_cpardiso-dir=/ccc/products/mkl-18.0.1.163/default/18.0.1.163/mkl <http://18.0.1.163/mkl> --with-scalapack-include=/ccc/products/mkl-18.0.1.163/default/18.0.1.163/mkl/include <http://18.0.1.163/mkl/include> --with-scalapack-lib="[/ccc/products/mkl-18.0.1.163/default/18.0.1.163/mkl/lib/intel64/libmkl_scalapack_lp64.so,/ccc/products/mkl-18.0.1.163/default/18.0.1.163/mkl/lib/intel64/libmkl_blacs_openmpi_lp64.so <http://18.0.1.163/mkl/lib/intel64/libmkl_scalapack_lp64.so,/ccc/products/mkl-18.0.1.163/default/18.0.1.163/mkl/lib/intel64/libmkl_blacs_openmpi_lp64.so>]" --with-fortran-bindings=0 PETSC_ARCH=arch-linux2-c-debug-bullxmpi
> [406]PETSC ERROR: #1 PCGAMGHashTableFind() line 106 in /ccc/work/cont003/rndm/rndm/petsc/include/petsc/private/pcgamgimpl.h
> [406]PETSC ERROR: #2 smoothAggs() line 526 in /ccc/work/cont003/rndm/rndm/petsc/src/ksp/pc/impls/gamg/agg.c
> [406]PETSC ERROR: #3 PCGAMGCoarsen_AGG() line 970 in /ccc/work/cont003/rndm/rndm/petsc/src/ksp/pc/impls/gamg/agg.c
> [406]PETSC ERROR: #4 PCSetUp_GAMG() line 518 in /ccc/work/cont003/rndm/rndm/petsc/src/ksp/pc/impls/gamg/gamg.c
> [406]PETSC ERROR: #5 PCSetUp() line 932 in /ccc/work/cont003/rndm/rndm/petsc/src/ksp/pc/interface/precon.c
> [406]PETSC ERROR: #6 KSPSetUp() line 381 in /ccc/work/cont003/rndm/rndm/petsc/src/ksp/ksp/interface/itfunc.c
> 
> For smaller problems, this works fine. Should I compile using 64 bit indices?
> I’m using -pc_type gamg -pc_gamg_threshold 0.8 -pc_gamg_agg_nsmooths 1 -pc_gamg_sym_graph true -pc_gamg_square_graph 10
> 
> Thanks,
> Pierre

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