[petsc-dev] features of GAMG

Hi, I'm trying different AMG (sequential) solvers as black-boxes preconditioners for almost incompressible elasticity in 3d with spectral elements; specifically, ML and HYPRE (both called from PETSc), but they don't provide good results (at least using them via the PETSc interface). I wish to test for new GAMG preconditioner from actual petsc-dev. I wish to test the solver either with essential boundary conditions on one face, or with pure neumann boundaries. Can you (I think Mark Adams is the one I'm talking with) give my some hints on the customization of the preconditioner? Regards, -- Stefano