[petsc-dev] Parmetis bug

[Mark Adams]

On Sat, Nov 9, 2019 at 10:51 PM Fande Kong <fdkong.jd at gmail.com> wrote:

> Hi Mark,
>
> Thanks for reporting this bug. I was surprised because we have sufficient
> heavy tests in moose using partition weights and do not have any issue so
> far.
>
>
I have been pounding on this code with elasticity and have not seen this
issue. I am now looking at Lapacianas and I only see it with pretty large
problems. The example below is pretty minimal (eg, it works with 16 cores
and it works with -dm_refine 4). I have reproduced this on Cori, SUMMIT and
my laptop.


> I will take a shot on this.
>

Thanks, I'll try to take a look at it also. I have seen it in DDT, but did
not dig further. It looked like a typical segv in ParMetis.


>
> Fande,
>
> On Sat, Nov 9, 2019 at 3:08 PM Mark Adams <mfadams at lbl.gov> wrote:
>
>> snes/ex13 is getting a ParMetis segv with GAMG and coarse grid
>> repartitioning. Below shows the branch and how to run it.
>>
>> I've tried valgrind on Cori but it gives a lot of false positives. I've
>> seen this error in DDT but I have not had a chance to dig and try to fix
>> it. At least I know it has something to do with weights.
>>
>> If anyone wants to take a shot at it feel free. This bug rarely happens.
>>
>> The changes use weights and are just a few lines of code (from 1.5 years
>> ago):
>>
>> 12:08 (0455fb9fec...)|BISECTING ~/Codes/petsc$ git bisect bad
>> 0455fb9fecf69cf5cf35948c84d3837e5a427e2e is the first bad commit
>> commit 0455fb9fecf69cf5cf35948c84d3837e5a427e2e
>> Author: Fande Kong <fdkong.jd at gmail.com>
>> Date:   Thu Jun 21 18:21:19 2018 -0600
>>
>>     Let parmetis and ptsotch take edge weights and vertex weights
>>
>>  src/mat/partition/impls/pmetis/pmetis.c | 7 +++++++
>>  src/mat/partition/impls/scotch/scotch.c | 6 +++---
>>  2 files changed, 10 insertions(+), 3 deletions(-)
>>
>> > mpiexec -n 32 ./ex13 -cells 2,4,4, -dm_refine 5 -simplex 0 -dim 3
>> -potential_petscspace_degree 1 -potential_petscspace_order 1 -pc_type gamg
>> -petscpartitioner_type simple -pc_gamg_repartition
>> true -check_pointer_intensity 0
>>
>
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