I ran it with -malloc_debug and it does not change anything.
The output is the following:
he absolute tolerance is 0.001
The relative tolerance is 0.001
The divergence tolerance is 10000
The maximum iterations is 10000
Initial load !
[0]PETSC ERROR:
------------------------------------------------------------------------
[0]PETSC ERROR: Caught signal number 11 SEGV: Segmentation Violation,
probably memory access out of range
[0]PETSC ERROR: Try option -start_in_debugger or -on_error_attach_debugger
[0]PETSC ERROR: or see https://urldefense.us/v3/__https://petsc.org/release/faq/*valgrind__;Iw!!G_uCfscf7eWS!ecHZVRiYJFEV3Ru8URyFbEGJ2vXQ2KQNNyMC0E_KEclprR38CfKltYBqj_PQOatAvKs-QLz5Xh161SwNgfph8H2kFhfcV5HZZemMgh7IVw$ and
https://urldefense.us/v3/__https://petsc.org/release/faq/__;!!G_uCfscf7eWS!ecHZVRiYJFEV3Ru8URyFbEGJ2vXQ2KQNNyMC0E_KEclprR38CfKltYBqj_PQOatAvKs-QLz5Xh161SwNgfph8H2kFhfcV5HZZekrkUwXlA$
[0]PETSC ERROR: --------------------- Stack Frames
------------------------------------
[0]PETSC ERROR: The line numbers in the error traceback are not always
exact.
[0]PETSC ERROR: #1 SNES callback function
[0]PETSC ERROR: #2 SNESComputeFunction() at
/home/daniel-pino/Software/Dependencies/petsc/src/snes/interface/snes.c:2489
[0]PETSC ERROR: #3 SNESSolve_KSPONLY() at
/home/daniel-pino/Software/Dependencies/petsc/src/snes/impls/ksponly/ksponly.c:27
[0]PETSC ERROR: #4 SNESSolve() at
/home/daniel-pino/Software/Dependencies/petsc/src/snes/interface/snes.c:4841
--------------------------------------------------------------------------
MPI_ABORT was invoked on rank 0 in communicator MPI_COMM_WORLD
Proc: [[27669,1],0]
Errorcode: 59
NOTE: invoking MPI_ABORT causes Open MPI to kill all MPI processes.
You may or may not see output from other processes, depending on
exactly when Open MPI kills them.
--------------------------------------------------------------------------
On 29/10/2024 20:17, Barry Smith wrote:
Hmm, cut and paste the output when it crashes.
Also run with -malloc_debug and see what happens
Barry
On Oct 29, 2024, at 3:13 PM, Daniel Pino Munoz
<daniel.pino_mu...@mines-paristech.fr> wrote:
Hi Barry,
Thanks for getting back to me!
I tried replacing KSPSetOperators(ksp, J, J); by SNESSetJacobian(snes,J,J,
MatMFFDComputeJacobian)
and I get the same result = It works in Debug mode but not in Release. I also
ran valgrind and it did not catch any memory problem.
Any ideas?
PS : You are right regarding the number of iterations of the non preconditioned
problem. In the previous version of the code that only used a KSP, I already
had to set -ksp_gmres_restart 100. But thanks for the heads up.
Best,
Daniel
On 29/10/2024 20:01, Barry Smith wrote:
Don't call
KSPSetOperators(ksp, J, J);
instead call
SNESSetJacobian(snes,J,J, MatMFFDComputeJacobian)
but I am not sure that would explain the crash.
BTW: since you are applying no preconditioner if the matrix is
ill-conditioned it may take many iterations or not converge. You can try
something like -ksp_gmres_restart 100 or similar value to try to improve
convergence (default is 30).
Barry
On Oct 29, 2024, at 12:37 PM, Daniel Pino Munoz
<daniel.pino_mu...@mines-paristech.fr> wrote:
Dear all,
I have a linear problem that I am currently solving with a KSP matrix-free.
I would like to move on to a non linear problem, so figure I could start by
solving the same linear problem using SNES. So I am setting the problem as
follows:
SNESCreate(PETSC_COMM_WORLD, &snes);
MatCreateShell(PETSC_COMM_WORLD, n_dofs, n_dofs, PETSC_DETERMINE, PETSC_DETERMINE,
&ctx, &J);
MatCreateShell(PETSC_COMM_WORLD, n_dofs, n_dofs, PETSC_DETERMINE, PETSC_DETERMINE,
&ctx, &B);
MatShellSetOperation(J, MATOP_MULT, (void (*)(void))(Multiplication));
MatCreateVecs(J, &x_sol, &b);
VecDuplicate(x_sol, &r);
SNESSetFromOptions(snes);
SNESSetFunction(snes, r, &(computeResidual), &ctx);
SNESSetUseMatrixFree(snes, PETSC_FALSE, PETSC_TRUE);
SNESGetLineSearch(snes, &linesearch);
SNESGetKSP(snes, &ksp);
KSPSetOperators(ksp, J, J);
KSPSetInitialGuessNonzero(ksp, PETSC_TRUE);
I tested it with a small problem (compiled in debug) and it works.
When I compiled it in Release, it crashes with a segfault. I tried running the
Debug version through valgrind, but even for a small problem, it is too slow.
So I was wondering if you guys could see any rocky mistake on the lines I used
above?
Otherwise, is there any example that uses a SNES combined with a matrix free
KSP operator?
Thank you,
Daniel
