[petsc-users] Imbalance in ParMETIS

[Eda Oktay]

Dear Matt,

In order to get a nice cut, I am trying to change the balance, that is why
I tried to change ubvec. But still I couldn't understand why it didn't
change anything.

I tried to change vertex weights but it only made Max and Min change but it
didn't change the cut.

Thanks,

Eda


On Fri, Jun 28, 2019, 1:49 PM Matthew Knepley <knepley at gmail.com> wrote:

> On Fri, Jun 28, 2019 at 5:38 AM Eda Oktay via petsc-users <
> petsc-users at mcs.anl.gov> wrote:
>
>> Hello everyone,
>>
>> I am trying to change load balance in ParMETIS in order to give different
>> number of elements to different processors. In the manual, it states that
>> changing "ubvec" parameter should work. So, instead of 1.05, I gave 1.2,1.5
>> and so on but load balance didn't change. I always get Max 5 Min 5 when I
>> view load balance. The partitioning part of my code is:
>>
>
> ParMetis is always balancing. ubvec changes the balance between having
> even partitions and a nice cut. If
> you want unbalanced partitions, you have to change the vertex weights.
>
>   Thanks,
>
>     Matt
>
>
>>  ierr = MatConvert(A,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);
>>   MatPartitioningViewImbalance(part,partitioning);
>>
>> What should I do? Why changing ubvec didn't change anything, am I
>> missing something?
>>
>> Thanks,
>>
>> Eda
>>
>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
> https://www.cse.buffalo.edu/~knepley/
> <http://www.cse.buffalo.edu/~knepley/>
>
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