Hi Bernd and Christoph,
Thank you for your reply.
In fact, the same problem occurred (computation stopped in a Newton
iteration without crashing) in a sequential run.
For the solver, we have this line in our problem.hh file
(SET_TYPE_PROP(HeterogeneousProblem, LinearSolver,
Dumux::AMGBackend<TypeTag> );) and #include
<dumux/linear/amgbackend.hh> without any other modification.
So by default, the solver is the BiCGSTABSolver.
I have installed and compiled SuperLU but I don't know how to link with
DUMUX. Can you give me please, the options to put in the file
optim.opts in the section "CMAKE_FLAGS" to link with SuperLU or UMFPack?
Best regards
Etienne
Le 13/12/2016 à 22:50, Bernd Flemisch a écrit :
Hi Etienne,
as Christoph points out, the effect you see is that a problem occurs on one
process and other processes are waiting. I don't expect the linear solver to
cause the deadlock, since quite some care is taken there to avoid exactly that.
I recommend that you recompile with debug options. This might give you a more
meaningful error message. If not, you have to enter the joy of parallel
debugging.
It is very unusual that the AMG is so much slower. As Christoph says, solving
directly on the coarsest level can be important. You can try to make a minimal
example on top of a standard Dumux model so that we can take a look.
Kind regards
Bernd
Tue, 13 Dec 2016 16:09:25 +0100
Christoph Grüninger <[email protected]> wrote:
Hi Etienne,
as I did never parallel runs with DuMuX myself, I can only guess.
My guess is, that your linear solver does not converge and you don't see
the error because some process is waiting for the result from a process
that terminated due to the failed convergence. So it will never
show the error or terminate.
For the AMG solver, are there some additional parameters to give?
Do you use SuperLU or UMFPack or an iterative method after you
preconditioned with AMG? Markus Blatt often advises to use the direct
methods as the iterative ones are prone to breakdown. Might be worth a try…
Bye
Christoph
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Bernd Flemisch phone: +49 711 685 69162
IWS, Universitaet Stuttgart fax: +49 711 685 67020
Pfaffenwaldring 61 email: [email protected]
D-70569 Stuttgart url: www.hydrosys.uni-stuttgart.de
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