Poor performance with BoomerAMG?

[Ben Tay]

Hi Knut,

I'm currently using boomeramg to solve my poisson eqn too. I'm using it 
on my structured C-grid. I found it to be faster than LU, especially as 
the grid size increases. However I use it as a preconditioner with GMRES 
as the solver. Have you tried this option? Although it's faster, the 
speed increase is usually less than double. It seems to be worse if 
there is a lot of stretching in the grid.

Btw, your mention using the DMMG framework and it takes less than a sec. 
What solver or preconditioner did you use? It's 4 times faster than GMRES...

thanks!

knutert at stud.ntnu.no wrote:
> Hello,
>
> I am trying to use the hypre multigrid solver to solve a Poisson 
> equation.
> However, on a test case with grid size 257x257 it takes 40 seconds to 
> converge
> on one processor when I run with
> ./run -ksp_type richardson -pc_type hypre -pc_type_hypre boomeramg
>
> Using the DMMG framework, the same problem takes less than a second,
> and the default gmres solver uses only four seconds.
>
> Am I somehow using the solver the wrong way, or is this performance 
> expected?
>
> Regards
> Knut Erik Teigen
>
>