Hi Martin,
Thank you for your reply,
Yes, I did this but I have always the same problem.
@+
Mustapha
Le 08/02/2017 à 10:20, Martin Schneider a écrit :
Hi Mustapha,
did you try to also change the CoarsenCriterion? You could try to
replace "Dune::Amg::SymmetricCriterion" with
"Dune::Amg::UnSymmetricCriterion". There might be some reason why a
symmetric preconditioner SSOR
is used for for the case of a symmetric CoarsenCriterion.
Regards,
Martin
On 02/08/2017 09:56 AM, Mustapha El Ossmani wrote:
Hi Christoph,
Thank you for your reply. Here are some precisions
* Do see this problem only in parallel or also in sequential code?
Only with AMG or also with GMRES and ILU?
We have this problem in both case (sequential and parrallel code)
*only*when we compile with *MPI* and only with *AMG* solver and
Dune::*SeqILU0* as Preconditioner. Contrariwise this problem does not
occur with SSOR as Preconditionner.
* Analyze the problem with Valgrind or AddressSanitizer. Having it
reduced might be beneficial.
We have run a simple test (co2 model in DUMUX)in some iterations with
valgrind and we obtained the messages that can be found in the
enclosed filewhich confirms that there is a loss of memory.
Have you ever met this issue ?
Best regards
M. El Ossmani
Le 07/02/2017 à 06:22, Christoph Grüninger a écrit :
Hi Mustapha,
I have never seen such problems but I am no solver expert. What you
can do:
* Do see this problem only in parallel or also in sequential code?
Only with AMG or also with GMRES and ILU?
* Reduce the problem as much as you can. The best would be a minimal
piece of software that only depends on Dune-istl that reads in your
matrix and repeatedly solves your linear system with the seen
undesired memory consumption. Not sure whether this is possible and
whether such minimal setup would still have the problem at all. When
you reduce your current problem, the problem might vanish, too. This
can help to find the cause of your issue.
* Analyze the problem with Valgrind or AddressSanitizer. Having it
reduced might be beneficial.
* Turning on all compiler warnings and carefully evaluating them
might help. But there are false positives but it can help.
* Maybe its worth repeating your question at the Dune mailing list
d...@dune-project.org <mailto:d...@dune-project.org> as there are
more Users and developers of istl.
Bye,
Christoph
Am 03.02.2017 um 11:14 schrieb Mustapha El Ossmani
<m.elossm...@ensam.umi.ac.ma <mailto:m.elossm...@ensam.umi.ac.ma>>:
Dear DuMu^X developers,
We are performing parallel computation with AMG solver. Due to
problems of convergence in the newton's method, in amgproperties.hh
we set the Preconditioner from Dune::SeqSSOR to Dune::SeqILU0 :
typedef
Dune::BlockPreconditioner<VType,VType,Comm,Dune::SeqSSOR<MType,VType,
VType> > Smoother;
// typedef
Dune::BlockPreconditioner<VType,VType,Comm,Dune::SeqILU0<MType,VType,
VType> > Smoother;
It seems that there is some problems of memory loss with ILU0
preconditionner. Indeed we can see that the memory of computation
is continually
increasing, until the computation stops with the following error
message :
Solve: M deltax^k = rslurmstepd: Job 936902 exceeded memory limit
(41146808 > 41058304), being killed
slurmstepd: Exceeded job memory limit
We can notice that this problem does not occur with SSOR as
Preconditionner.
Have you ever met this issue ?
Best regards
M. El Ossmani
University of Pau
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