[petsc-users] ParMETIS vs. CHACO when no partitioning is made

[Fande Kong]

IIRC, Chaco does not produce an arbitrary number of subdomains. The number
needs to be like 2^n.

ParMETIS and PTScotch are much better, and they are production-level code.
If there is no particular reason, I would like to suggest staying with
ParMETIS and PTScotch.

Thanks,

Fande,



On Fri, Aug 14, 2020 at 10:07 AM Eda Oktay <eda.oktay at metu.edu.tr> wrote:

> Dear Barry,
>
> Thank you for answering. I am sending a sample code and a binary file.
>
> Thanks!
>
> Eda
>
> Barry Smith <bsmith at petsc.dev>, 14 Ağu 2020 Cum, 18:49 tarihinde şunu
> yazdı:
>
>>
>>    Could be a bug in Chaco or its call from PETSc for the special case of
>> one process. Could you send a sample code that demonstrates the problem?
>>
>>   Barry
>>
>>
>> > On Aug 14, 2020, at 8:53 AM, Eda Oktay <eda.oktay at metu.edu.tr> wrote:
>> >
>> > Hi all,
>> >
>> > I am trying to try something. I am using the same MatPartitioning codes
>> for both CHACO and ParMETIS:
>> >
>> > ierr =
>> MatConvert(SymmA,MATMPIADJ,MAT_INITIAL_MATRIX,&AL);CHKERRQ(ierr);
>> >   ierr = MatPartitioningCreate(MPI_COMM_WORLD,&part);CHKERRQ(ierr);
>> >   ierr = MatPartitioningSetAdjacency(part,AL);CHKERRQ(ierr);
>> >
>> >   ierr = MatPartitioningSetFromOptions(part);CHKERRQ(ierr);
>> >   ierr = MatPartitioningApply(part,&partitioning);CHKERRQ(ierr);
>> >
>> > After obtaining the IS, I apply this to my original nonsymmetric matrix
>> and try to get an approximate edge cut.
>> >
>> > Except for 1 partitioning, my program completely works for 2,4 and 16
>> partitionings. However, for 1, ParMETIS gives results where CHACO I guess
>> doesn't since I am getting errors about the index set.
>> >
>> > What is the difference between CHACO and ParMETIS that one works for 1
>> partitioning and one doesn't?
>> >
>> > Thanks!
>> >
>> > Eda
>>
>>
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