Hi, I'm going to solve a Schur complement in my preconditioner for SUPG stabilized fluid solver and will be using ILU(0) decomposition. Since the BlockJacobi does not turn out to work well, I wrote a wrapper for Pilut, which is a package for ILUT decomposition in Hypre and wrapped by PETSc. I tested my Pilut preconditioner with tutorial step-17 (the MPI elastic problem) and everything looks ok. However, when I apply it to my own code, running with 2 ranks takes more time than 1, specifically on solving the Schur complement where my Pilut is applied. I tried to output the total iteration number of the solver, but with more ranks, actually less iterations are used. I don't understand why less iterations take more time. Is there any potential reason for that? Something that came up to my mind, but I'm not sure: my Schur complement is actually not a matrix, but a derived class that only has definition for vmult. For that reason, my solver is a dealii:solverGMRES instead of PETScWrappers::solverGMRES. However, my results in testing with step-17 did not show significant differences between these two.
Thanks! Feimi -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
