[petsc-users] Prometheus vs GAMG for elasticity/plasticity problems

[Thomas Gross]

Dear petsc users/developers,

I am using petsc in a parallel FEAP framework (http://www.ce.berkeley.edu/projects/feap/) for mechanics oriented problems (mainly linear elasticity or plasticity).
In earlier petsc versions (3.2.7) I always used the petsc options:
-ksp_type cg -pc_type prometheus (with standard settings) and achieved a great level of performance.

After updating to petsc 3.4.3, where the “Prometheus” preconditioner was replaced by “GAMG”, I can not reach the same level of performance. My settings are:
-ksp_type cg -pc_type gamg -pc_gamg_type agg -pc_gamg_agg_nsmooths 1 (settings recommended for FEAP).

Is there a set of GAMG settings, which are equivalent to the standard Prometheus settings?

Many thanks and best regards,
Thomas