Hi, Not on the PETSc team but some experience with these two multilevel preconditioners. For starters take a look at this publication by one of the HYPRE team members on parameter choices for 2D and 3D Poisson problems that deliver the best performance. Pay particular attention to p. 18-22. There are many knobs with these solvers (in particular BoomerAMG) and they may need tweaking to improve performance.
https://computation.llnl.gov/casc/linear_solvers/pubs/yang1.pdf Also, what is your definition of poor scalability? With respect to increasing processor count (i.e., parallel scalability) or with respect to performance based on increasing problem size? Both of these preconditiioners have been thoroughly tested for Poisson-style problems and I'd be surprised if you don't get (at least) good scalability with respect to problem size? Travis ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Travis Austin, Ph.D. Tech-X Corporation 5621 Arapahoe Ave, Suite A Boulder, CO 80303 austin at txcorp.com ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ On May 19, 2011, at 5:56 PM, Li, Zhisong (lizs) wrote: > Hi, Petsc Team, > > Recently I tested my 3D structured Poisson-style problem with ML and > BoomerAMG preconditioner respectively. In comparison, ML is more efficient > in preconditioning and RAM usage, but it requires 2 times more iterations on > the same KSP solver, bringing down the overall efficiency. And both PCs > don't scale well. I wonder if there's any specific approach to optimizing ML > to reduce KSP iterations by setting certain command line options. > > I also saw in some previous petsc mail archives mentioning the "local > preconditioner". As some important PC like PCILU and PCICC are not available > for parallel processing, it may be beneficial to apply them as local > preconditioners. The question is how to setup a local preconditioner? > > > Thank you veru much. > > > > Zhisong Li -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20110519/fd5a3916/attachment.htm>
