dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Thu, May 22, 2008 at 11:26:41AM +0200, Dag Lindbo wrote:
> DOLFIN wrote:
> > One or more new changesets pushed to the primary dolfin repository.
> > A short summary of the last three changesets is included below.
> > 
> > changeset:   4224:c5a7da38ff2c966e5f2483b5232993fb75ac6aa1
> > tag:         tip
> > user:        Anders Logg <logg@xxxxxxxxx>
> > date:        Thu May 22 10:19:48 2008 +0200
> > files:       dolfin/fem/DirichletBC.cpp dolfin/fem/DirichletBC.h
> > description:
> > Major cleanup of DirichletBC:
> >  - Store boundary facets in array, common for all different representations
> >  - BCs may now be specified in 3 differenet ways: SubDomain, MeshFunction, or as Mesh data
> >  - Should speed up repeated application of BCs
> >  - Tested on a few different applications, but please check that nothing broke.
> >    In particular, geometric and pointwise application has not been tested.
> 
> Noting broke here!

ok, nice. Thanks for checking (Kristian also).

> However, I'm not seeing the speedup... (and I'm reapplying the dirichlet
> bcs every timestep). My code spends a good 30% of runtime applying
> dirichlet BCs (linear systems are pre-factorized so the solve step takes
> no time). Any hints?

The speedup may not be noticeable if a lot of time is spent on
evaluating the function. Would be interesting to profile.

The difference from before is that each time apply() is called, we
only iterate over the actual facets included in your subdomain of the
boundary, not the entire mesh and then skipping those facets which
don't belong to your boundary. Also, depending on which type of search
("topological", "geometric", "pointwise"), the new implementation
should avoid initializing mesh facets.

-- 
Anders