Re: Using parMetis in petsc for ordering

[Dimitri Lecas <dimitri.lecas@xxxxxxx>]

Barry Smith a écrit :
>   1) The PETSc LU and Cholesky solvers only run sequentially.
>   2) The parallel LU and Cholesky solvers PETSc interfaces to, SuperLU_dist,
>      MUMPS, Spooles, DSCPACK do NOT accept an external ordering provided for
>      them.
>  
>    Hence we do not have any setup for doing parallel matrix orderings for
> factorizations, since we cannot use them. We could allow calling a parallel
> ordering but I'm not sure what it would be useful for.
>
>    Barry
>
>   
Ok i see that i was looking for a wrong direction.

Just in ksp/examples/tutorials/ex10.c, Partitioning is used on the 
linear system matrix. I don't understand why ?

What i understand it's, with MatPartitioning we try to partitioning the 
graph build  from the matrix (vertices is the row/columns and edge 
between i and j if aij or aji is non zero value). But in my mind, a good 
partitioning for solving linear system with iterative algorithm is to 
load balance the non zero value between processors, so we have to use 
weight, number of non zero value in the row, to have a good partitioning.
Do i have it right ?

--
Dimitri Lecas