> On Tue, Feb 19, 2008 at 09:18:54AM +0100, Johan Hoffman wrote: >> > On Mon, Feb 18, 2008 at 04:35:54PM +0100, Johan Hoffman wrote: >> >> > This is good juncture at which re-focus on important goals for a >> >> hopefully not too distant next release. Three priorities that I see >> are: >> >> > >> >> > - New build system. >> >> > >> >> > - Improved support for parallel assembly and solve. The class >> Function >> >> will probably need the most work. Good goals would be to get Poisson >> and >> >> elasticity demos running in parallel. >> >> >> >> I thought the Poisson problem was running, and showing good parallel >> >> scaling? Or maybe that was a test outside the dolfin-dev demos? >> > >> > The demo is in src/demo/fem/assembly/. >> >> Ok, so the matrix assembly is working and is implemented as a demo, but >> solve is missing. > > Two things are missing: solve and handling forms with coefficients in > parallel (the Vector in DiscreteFunction holding the dofs should be > parallel). > > Garth has done parallel solve (with PETSc) in > src/sandbox/passembly/main.cpp > so it shouldn't be much work to get the solve part going.
Ok. >> >> We (Nicklas) have now a preliminary distributed parallel >> implementation >> >> running for Poisson and a Unicorn flow solver. The structure is still >> >> quite messy and the partitioning is based on Metis, but we expect it >> to >> >> be >> >> integrated with DOLFIN in the coming months, hopefully before the >> >> summer. >> > >> > Could this be done in small pieces? I'm a little worried about seeing >> > big changesets that add things to the mesh classes. >> >> Yes, we need to figure out how this should be done to best fit with the >> existing mesh classes. When we have cleaned up the code we will take >> that >> discussion here at the dolfin mailing list so that we can agree on a >> solution. > > Excellent. > >> >> When the structure is more clear we can discuss on the mailing list >> how >> >> to >> >> best incorporate this into DOLFIN. Apart from the structure of the >> >> implementation we are also focusing on distributed local mesh >> >> refinement. >> > >> > Great. >> > >> > What is the difference from what we have now? Is it the same but with >> > a distributed mesh (so each processor just sees the local part, not >> > the whole mesh)? Or is it something different? >> >> I think the main issues are to handle refinement over >> partition-boundaries, and efficient re-partitioning after refinement >> (for >> load-balancing). > > ok, we haven't considered this at all. > >> > I think what we have now can be fairly easily extended to a >> > distributed mesh without any (significant) changes to the mesh >> > classes. The key point is to build the DofMap in parallel. Take a look >> > here, in particular Section 6 and Algorithm 5: >> > >> > http://simula.no/research/scientific/publications/Simula.SC.75 >> > >> >> Seems I need a username/password for this. > > Sorry, try here: > > http://home.simula.no/~logg/tmp/ Thanks; works better! /Johan > -- > Anders > > >> /Johan >> >> >> > - Testing of QuadratureFunction and adding corresponding demos. >> >> > >> >> > Another point is to add Trilinos as a supported linear algebra back >> >> end. >> >> How does this tie up with closer links to PyCC? >> >> > >> >> > Garth >> >> >> >> - Something else that I think is important is to include geometry in >> >> DOLFIN. We were to start such a project before Christmas, but we lost >> >> the >> >> msc student that was supposed to work on this. I would expect that we >> >> restart this later this spring. Basically we need to import >> CAD-geometry >> >> (or other geometry descriptions), create an internal DOLFIN format >> >> (typically based on NURBS or similar) with a Geometry-class. Typical >> >> functionality needed is then to project a point onto the surface >> >> geometry. >> > >> > That would be nice. >> > >> > >> > >> >> /Johan >> >> >> >> >> >> > _______________________________________________ >> >> > 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 >> > _______________________________________________ >> > 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 > _______________________________________________ > 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
