On Wednesday 17 December 2008 20:19:52 Anders Logg wrote: > On Wed, Dec 17, 2008 at 08:13:03PM +0100, Johan Hake wrote: > > On Wednesday 17 December 2008 19:20:11 Anders Logg wrote: > > > Ola and I have now finished up the first round of getting DOLFIN to > > > run in parallel. In short, we can now parse meshes from file in > > > parallel and partition meshes in parallel (using ParMETIS). > > > > > > We reused some good ideas that Niclas Jansson had implemented in > > > PXMLMesh before, but have also made some significant changes as > > > follows: > > > > > > 1. The XML reader does not handle any partitioning. > > > > > > 2. The XML reader just reads in a chunk of the mesh data on each > > > processor (in parallel) and stores that into a LocalMeshData object > > > (one for each processor). The data is just partitioned in blocks so > > > the vertices and cells may be completely unrelated. > > > > > > 3. The partitioning takes place in MeshPartitioning::partition, > > > which gets a LocalMeshData object on each processor. It then calls > > > ParMETIS to compute a partition (in parallel) and then redistributes > > > the data accordingly. Finally, a mesh is built on each processor using > > > the local data. > > > > > > 4. All direct MPI calls (except one which should be removed) have been > > > removed from the code. Instead, we mostly rely on > > > dolfin::MPI::distribute which handles most cases of parallel > > > communication and works with STL data structures. > > > > > > 5. There is just one ParMETIS call (no initial geometric > > > partitioning). It seemed like an unnecessary step, or are there good > > > reasons to perform the partitioning in two steps? > > > > > > For testing, go to sandbox/passembly, build and then run > > > > > > mpirun -n 4 ./demo > > > ./plot_partitions 4 > > > > Looks beautiful! > > > > I threw a 3D mesh of 160K vertices onto it, and it was partitioned nicely > > in some 10 s, on my 2 core laptop. > > > > Johan > > Nice, in particular since we haven't run any 3D test cases ourselves, > just a tiny mesh of the unit square... :-)
Yes I thought so too ;) Johan _______________________________________________ DOLFIN-dev mailing list [email protected] http://www.fenics.org/mailman/listinfo/dolfin-dev
