superlu_dist options

[Satish Balay]

Just a note about scalability: its a function of the hardware as
well.. For proper scalability studies - you'll need a true distributed
system with fast network [not SMP nodes..]

Satish

On Fri, 8 May 2009, Fredrik Bengzon wrote:

> Hong,
> Thank you for the suggestions, but I have looked at the EPS and KSP objects
> and I can not find anything wrong. The problem is that it takes longer to
> solve with 4 cpus than with 2 so the scalability seems to be absent when using
> superlu_dist. I have stored my mass and stiffness matrix in the mpiaij format
> and just passed them on to slepc. When using the petsc iterative krylov
> solvers i see 100% workload on all processors but when i switch to
> superlu_dist only two cpus seem to do the whole work of LU factoring. I don't
> want to use the krylov solver though since it might cause slepc not to
> converge.
> Regards,
> Fredrik
> 
> Hong Zhang wrote:
> > 
> > Run your code with '-eps_view -ksp_view' for checking
> > which methods are used
> > and '-log_summary' to see which operations dominate
> > the computation.
> > 
> > You can turn on parallel symbolic factorization
> > with '-mat_superlu_dist_parsymbfact'.
> > 
> > Unless you use large num of processors, symbolic factorization
> > takes ignorable execution time. The numeric
> > factorization usually dominates.
> > 
> > Hong
> > 
> > On Fri, 8 May 2009, Fredrik Bengzon wrote:
> > 
> > > Hi Petsc team,
> > > Sorry for posting questions not really concerning the petsc core, but when
> > > I run superlu_dist from within slepc I notice that the load balance is
> > > poor. It is just fine during assembly (I use Metis to partition my finite
> > > element mesh) but when calling the slepc solver it dramatically changes. I
> > > use superlu_dist as solver for the eigenvalue iteration. My question is:
> > > can this have something to do with the fact that the option 'Parallel
> > > symbolic factorization' is set to false? If so, can I change the options
> > > to superlu_dist using MatSetOption for instance? Also, does this mean that
> > > superlu_dist is not using parmetis to reorder the matrix?
> > > Best Regards,
> > > Fredrik Bengzon
> > > 
> > > 
> > 
> 
>