Hi Ben, Thank you for answering. With gmres and boomeramg I get a run time of 2s, so that is much better. However, if I increase the grid size to 513x513, I get a run time of one minute. With richardson, it fails to converge. LU gives 6 seconds, CG and ICC gives 7s, and the DMMG solver 3s for the 513x513 problem.
When using the DMMG framework, I just used the default solvers. I use the Galerkin process to generate the coarse matrices for the multigrid cycle. Best, Knut Siterer Ben Tay <zonexo at gmail.com>: > 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 >> >>
