> On Sep 5, 2018, at 3:50 AM, Edoardo alinovi <[email protected]> wrote:
>
> Dear users,
>
> I am doing some testing of my FV code, using petsc for the linear systems
> solution. Actually, I am running a small problem (10k cells) in parallel with
> 4 processors. The solution is ok, but I have a question about hypre
> preconditioning performance. I am using PCHYPRE with its default settings for
> the solution of pressure-correction equation. What I am getting is that the
> multigrid preconditioning is significantly slower than block jacoby in
> solving the equation even if the iteration needed to converge are ten time
> the AMG's one (50 vs 3-4). Is this related to the small size of the problem?
Yes, compare on realistic size problems, and keep at least 10,000 degrees of
freedom per processor. Run on say 100 MPI processes min.
Barry
>
> Many thanks for the advices,
>
> Edo
>
> ------
>
> Edoardo Alinovi, Ph.D.
>
> DICCA, Scuola Politecnica
> Universita' di Genova
> 1, via Montallegro
> 16145 Genova, Italy
>
> email: [email protected]
> Tel: +39 010 353 2540
>
>
