dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Sun, May 18, 2008 at 09:40:34PM +0200, Dag Lindbo wrote:
> > On Sun, May 18, 2008 at 09:07:08PM +0200, Dag Lindbo wrote:
> >> >
> >> > Dag: A test suite/benchmark would be very good to have. We need to
> >> > have something in bench/fem/assembly that we can trust and run
> >> > regularly to make sure we don't have regressions.
> >> >
> >>
> >> Here is a suite of performance tests for the dolfin assembler:
> >> http://www.csc.kth.se/~dag/dolfin/dolfin_assembler_bench.tar.gz
> >>
> >> It does seven tests. Assembly and reassembly of the following (bilinear)
> >> forms:
> >> Elasticity (3d), Incompressible NS Momentum (3d), Laplace on linear
> >> (2d),
> >> Laplace on quadratic (2d), Laplace on cubic (2d), Stokes TH (2d), Stokes
> >> stabilized (2d). This seems to me to be a blend of different types of
> >> forms.
> >>
> >> The design of these tests is as modular as possible, so one can easily
> >> add
> >> more tests. The top-level SConstruct builds the whole thing. Run with
> >> run_tests.py
> >>
> >> The output as produced by by workstation (2.4GHz Core2Duo, 2gb ddr2,
> >> 32bit
> >> os) using the uBlas backend:
> >> http://www.csc.kth.se/~dag/dolfin/results_uBlas_opt
> >> There clearly is a spread in assembler performance for different forms.
> >>
> >> I suspect that you want to tweak the assembly_tester function to make it
> >> backend-invariant.
> >>
> >> Enjoy!
> >> /Dag
> >
> > Nice. Have you used anything backend-specific? Otherwise it would be
> > nice to present the results for all backends. This should be fairly
> > simple to do using the newly added option to specify the backend
> > dynamically:
> >
> >   dolfin_set("linear algebra backend", "PETSc");
> >   // Run code, using Vector and Matrix
> >
> >   dolfin_set("linear algebra backend", "uBLAS");
> >   // Run code, using Vector and Matrix
> >
> >   dolfin_set("linear algebra backend", "Epetra");
> >   // Run code, using Vector and Matrix
> >
> 
> I had to pick out the underlying ublas::Matrix<> in order to get the
> number of nonzero elements, since I could not find such a function in the
> generic interface. /Dag

I think we need to add something to the GenericMatrix interface to
extract this. My suggestion would be to add a function that can be
called to compute the sparsity pattern for any matrix. We can
currently initialize a matrix from a sparsity pattern but it would be
good to be able to do it the other way around, initializing a sparsity
pattern from a matrix.

In the meantime, maybe you could just iterate over the rows, call
getRow() and add columns.size()?

-- 
Anders