[petsc-users] Imbalance in ParMETIS

[Matthew Knepley]

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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