> On Thu, Aug 14, 2008 at 11:48:14AM +0200, Johan Hoffman wrote: >> > On Wed, Aug 13, 2008 at 2:57 PM, Johan Hoffman <[EMAIL PROTECTED]> >> > wrote: >> > >> >> > >> >> > >> >> > Johan Hoffman wrote: >> >> >>> >> >> >>> Anders Logg wrote: >> >> >>>> On Tue, Jun 17, 2008 at 02:45:41PM +0100, Garth N. Wells wrote: >> >> >>>>> It would be useful to lay out a plan for tackling DofMaps. >> Getting >> >> >>>>> this >> >> >>>>> right is the key to parallel assembly, assembly optimisations >> and >> >> >>>>> applying Dirichlet boundary conditions by eliminating Dirichlet >> >> dofs >> >> >>>>> from the global system. >> >> >>>>> >> >> >>>>> I'm happy to take a look, but I'll need some time because I've >> >> lost >> >> >>>>> my >> >> >>>>> overview of DofMaps. If someone else is already on top of it, >> I'd >> >> be >> >> >>>>> happy to provide feedback. >> >> >>>>> >> >> >>>>> Garth >> >> >>>> I won't have time to look at it until after the summer and I >> >> haven't >> >> >>>> started. >> >> >>>> >> >> >>>> Anyway, I think we should wait until after the next release >> until >> >> we >> >> >>>> start messing with the dof maps. >> >> >>>> >> >> >>>> Are there any issues we need to sort out before releasing 0.8? >> I'm >> >> >>>> thinking about a new release some time this or next week. >> >> >>>> >> >> >>>> One is to fix the bug in DirichletBC, but other than that? >> >> >>>> >> >> >>> Now would be a good time for a release so I can start messing >> with >> >> >>> DofMaps. >> >> >>> >> >> >>> Garth >> >> >> >> >> >> Has anything more been done about the DofMap design? During the >> >> summer >> >> >> Niclas has extended to general elements his adaptive algorithm for >> >> >> distributed parallel computing, so we are now ready to start >> messing >> >> >> with >> >> >> the DofMaps in order to implement his algorithm in DOLFIN. >> >> >> >> >> > >> >> > It has been given some thought, but no changes have been made in >> the >> >> > code yet. >> >> >> >> Ok. Any threads on the list to point to where this is discussed? >> >> >> >> If you have something already, I would suggest making it >> >> > publicly available somewhere for feedback before starting work on >> >> DOLFIN. >> >> >> >> It is a refinement and generalization of the thesis work of Niclas >> >> Jansson >> >> which was discussed on the list before the summer. Is is outlined in >> his >> >> report: >> >> >> >> http://www.nada.kth.se/utbildning/grukth/exjobb/rapportlistor/2008/rapporter08/jansson_niclas_08051.pdf >> >> >> >> My announcement here was to initiate a discussion of the detailed >> >> implementation, and to check if other DOLFIN-people were working on >> >> similar stuff to avoid double/conflicting development. >> >> >> >> /Johan >> >> >> > >> > Very good. We were about to start on this task, so now a good point in >> > time >> > to join forces. >> > As a starting point, it would be nice to agreeing on what data is >> needed >> > in >> > addition to the partitioned meshes to construct the global dofmap. >> I.e. >> > which MeshFunctions to construct during the mesh paritioning process. >> Are >> > you people using the same {T,S,F} input as Anders describes in >> Algorithm 5 >> > in his paper? >> >> We have discussed this, and it seems that for our adaptive algorithms we >> need some more info. Basically, we have two aims: >> >> 1. Fully distributed computing (no collection of data on one processor) >> 2. Possibility for dynamic load balancing >> >> To realize 1-2 we need information on the processor ownership of >> entities, >> and for resdistributing the mesh we need global vertex numbering. That >> is, >> we would need something like: {T,S,F,V,O}, where V is global vertex >> number >> and O is information whether boundary (between processors) vertices are >> own by the processor or if they are ghost nodes. > > How do you deal with global edge or face numbers?
I believe this is rebuilt from global vertex numbers. > My suggestion is to start without a global numbering and then build it > (in parallel). I am not sure how from only local info you can construct information on which boundary vertices are owned by which processes? >> Possibly this is too much information, since for example S,F can be >> computed from V,O, but by storing all info faster algorithms can be >> constructed, so there is a trad-off between speed and memory. >> >> What do you say? > > If you have something that works, just send us a patch so we can try it. Niclas can send you his code. /Johan > -- > Anders > _______________________________________________ > DOLFIN-dev mailing list > [email protected] > http://www.fenics.org/mailman/listinfo/dolfin-dev > _______________________________________________ DOLFIN-dev mailing list [email protected] http://www.fenics.org/mailman/listinfo/dolfin-dev
