[petsc-users] use Superlu as ilu preconditioner
Ping Rong
ping.rong at tuhh.de
Wed Jul 27 13:10:31 CDT 2011
Dear Hong,
thank you very much for your time. Can you tell me when should
KSPSetFromOptions(ksp) be called?
well, libMesh has a class called "petsc_linear_solver", in its original
code KSPSetFromOptions(ksp) is called while the object is created. I
couldn't get any output, when I run the program with the option
-pc_type ilu -pc_factor_mat_solver_package superlu
-mat_superlu_ilu_droptol 0.1 -ksp_view
The actual solve() function of the "petsc_linear_solver" contains the
similar code as in the ex2.c
...
ierr = KSPSetOperators(_ksp, matrix->mat(), precond->mat(),
this->same_preconditioner
? SAME_PRECONDITIONER : DIFFERENT_NONZERO_PATTERN);
CHKERRABORT(libMesh::COMM_WORLD,ierr);
// Set the tolerances for the iterative solver. Use the user-supplied
// tolerance for the relative residual & leave the others at default
values.
ierr = KSPSetTolerances (_ksp, tol, PETSC_DEFAULT, PETSC_DEFAULT,
max_its);
CHKERRABORT(libMesh::COMM_WORLD,ierr);
ierr = KSPSetFromOptions (_ksp); <-------------- I added these two
lines,
CHKERRABORT(libMesh::COMM_WORLD,ierr); <-------------- then I got
proper output.
// Solve the linear system
ierr = KSPSolve (_ksp, rhs->vec(), solution->vec());
CHKERRABORT(libMesh::COMM_WORLD,ierr);
....
The problem is that I have to solve a multiple frequency system, and for
each frequency I have several RHS. The same ksp context is used to solve
the systems repeatedly. I always call KSPSetOperators() with the option
DIFFERENT_NONZERO_PATTERN for the first RHS and SAME_PRECONDITIONER for
the rest, since the system matrix remains the same. For the first
frequency, everything is fine, both DIFFERENT_NONZERO_PATTERN and
SAME_PRECONDITIONER options. I got following output from the -ksp_view.
...
PC Object:
type: ilu
ILU: out-of-place factorization
0 levels of fill
tolerance for zero pivot 1e-12
using diagonal shift to prevent zero pivot
matrix ordering: natural
factor fill ratio given 0, needed 0
Factored matrix follows:
Matrix Object:
type=seqaij, rows=2883, cols=2883
package used to perform factorization: superlu
<---------------- superlu is properly set
....
but when the second frequency comes up, KSPSetOperators() is called
again with DIFFERENT_NONZERO_PATTERN option for the first RHS. the
command line option doesn't seem to work anymore.
...
PC Object:
type: ilu
ILU: out-of-place factorization
0 levels of fill
tolerance for zero pivot 1e-12
using diagonal shift to prevent zero pivot
matrix ordering: natural
factor fill ratio given 1, needed 1
Factored matrix follows:
Matrix Object:
type=seqaij, rows=2883, cols=2883
package used to perform factorization: petsc <------------
not superlu anymore
...
and then for the second RHS, when it calls KSPSetOperators(ksp) in the
solve() routine, petsc throws the following error message.
[0]PETSC ERROR: --------------------- Error Message
------------------------------------
[0]PETSC ERROR: Object is in wrong state!
[0]PETSC ERROR: Cannot change solver matrix package after PC has been
setup or used!
[0]PETSC ERROR:
------------------------------------------------------------------------
[0]PETSC ERROR: Petsc Release Version 3.1.0, Patch 8, Thu Mar 17
13:37:48 CDT 2011
[0]PETSC ERROR: See docs/changes/index.html for recent updates.
[0]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
[0]PETSC ERROR: See docs/index.html for manual pages.
[0]PETSC ERROR:
------------------------------------------------------------------------
[0]PETSC ERROR: ./PLTMainTest.opt on a linux-gnu named abe-vm by mubpr
Wed Jul 27 19:41:22 2011
[0]PETSC ERROR: Libraries linked from
/home/mubpr/libs/petsc/linux-gnu-acml-shared-opt/lib
[0]PETSC ERROR: Configure run at Tue Jul 26 22:09:39 2011
[0]PETSC ERROR: Configure options
--with-blas-lapack-lib=/home/mubpr/libs/acml/gfortran64_mp/lib/libacml_mp.so
--with-blas-lapack-include=/home/mubpr/libs/acml/gfortran64_mp/include
--with-scalar-type=complex --with-clanguage=c++
--with-mpi-dir=/home/mubpr/libs/mpich2 --download-superlu=yes
--with-superlu=1 --download-parmetis=yes --with-parmetis=1
--download-superlu_dist=yes --with-superlu_dist=1 --download-mumps=yes
--with-mumps=1 --download-blacs=yes --with-blacs=1
--download-scalapack=yes --with-scalapack=1 --download-spooles=yes
--with-spooles=1 --download-umfpack=yes --with-umfpack=1
--with-debugging=no --with-shared=1
[0]PETSC ERROR:
------------------------------------------------------------------------
[0]PETSC ERROR: PCFactorSetMatSolverPackage_Factor() line 183 in
src/ksp/pc/impls/factor/factimpl.c
[0]PETSC ERROR: PCFactorSetMatSolverPackage() line 276 in
src/ksp/pc/impls/factor/factor.c
[0]PETSC ERROR: PCSetFromOptions_Factor() line 275 in
src/ksp/pc/impls/factor/factimpl.c
[0]PETSC ERROR: PCSetFromOptions_ILU() line 112 in
src/ksp/pc/impls/factor/ilu/ilu.c
[0]PETSC ERROR: PCSetFromOptions() line 185 in src/ksp/pc/interface/pcset.c
[0]PETSC ERROR: KSPSetFromOptions() line 323 in src/ksp/ksp/interface/itcl.c
[0]PETSC ERROR: User provided function() line 696 in
"unknowndirectory/"src/solvers/petsc_linear_solver.C
Any idea what the problem may be? I would be very grateful, if you can
give me any hint. thanks alot
best regards
Ping
Am 27.07.2011 04:13, schrieb Hong Zhang:
> Did you call KSPSetFromOptions(ksp)?
> Run your code with '-options_table' to dump list of options inputted
> or '-options_left' to dump list of unused options.
>
> I tested with petsc-3.1/src/ksp/ksp/examples/tutorials/ex2.c:
> ./ex2
> ...
> SuperLU run parameters:
> ...
> ILU_DropTol: 0.1
> ILU_FillTol: 0.01
> ILU_FillFactor: 10
> ILU_DropRule: 9
> ILU_Norm: 2
> ILU_MILU: 2
>
> Hong
>
> On Tue, Jul 26, 2011 at 3:53 PM, Ping Rong<ping.rong at tuhh.de> wrote:
>> Dear developers,
>>
>> I have compiled petsc-3.1-p8 for a while. Now I would like to use superlu as
>> an ilu preconditioner, since it offers the drop tolerance option. I have
>> read in a thread
>> (https://lists.mcs.anl.gov/mailman/htdig/petsc-users/2010-December/007439.html)
>> that one can run the code with option
>>
>> -pc_type ilu -pc_factor_mat_solver_package superlu -mat_superlu_ilu_droptol
>> <>
>>
>> to setup the ilu preconditioner. I also use the option "-help |grep superlu"
>> to check the settings. However, no matter how I change the value of
>> -mat_superlu_ilu_droptol, I always got the same result
>> ...
>> -mat_superlu_lwork<0>: size of work array in bytes used by factorization
>> (None)
>> -mat_superlu_ilu_droptol<0.0001>: ILU_DropTol (None)
>> -mat_superlu_ilu_filltol<0.01>: ILU_FillTol (None)
>> ...
>> I dont know whether I understand it correctly. But it seems to me the value
>> of the droptol has never been changed. In that maillist thread, it was also
>> mentioned that the dev-version is recommended, because of some bugs in the
>> superlu interface. I have then compiled the current dev-version. but the
>> problem is my program is based on another library (libMesh) which uses petsc
>> as a solver package. Since some of the interfaces have been changed in the
>> dev-version, I would not be able to compile the libMesh with petsc anymore.
>> Is there anyway I can correct the superlu interface in the 3.1-p8 version
>> directly? Any help will be appreciated!!
>>
>> Best regards
>>
>> --
>> Ping Rong, M.Sc.
>> Hamburg University of Technology
>> Institut of modelling and computation
>> Denickestraße 17 (Room 3031)
>> 21073 Hamburg
>>
>> Tel.: ++49 - (0)40 42878 2749
>> Fax: ++49 - (0)40 42878 43533
>> Email: ping.rong at tuhh.de
>>
>>
--
Ping Rong, M.Sc.
Hamburg University of Technology
Institut of modelling and computation
Denickestraße 17 (Room 3031)
21073 Hamburg
Tel.: ++49 - (0)40 42878 2749
Fax: ++49 - (0)40 42878 43533
Email: ping.rong at tuhh.de
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