On Dec 23, 2011, at 10:53 AM, Jed Brown wrote: > On Fri, Dec 23, 2011 at 09:50, Mark F. Adams <mark.adams at columbia.edu> > wrote: > Humm, my G-S in not in PETSc and it is perfectly scalable. It does have more > complex communication patterns but they are O(1) in latency and bandwidth. > I'm not sure I understand your description above. > > It was more like, here's something that perhaps we want to put in PETSc, what > rich communication pattern does it use, such that, if provided, the > implementation would be simple?
There is the implementation in Prometheus that uses my C++ linked lists and hash tables. I would like to implement this with STLs. I also hack into MPIAIJ matrices to provide a primitive of applying G-S on an index set of local vertices, required for the algorithm. This should be rethought. I would guess that it would take about a week or two to move this into PETSc. The complex communication required make this code work much better with large subdomains, so it is getting less attractive in a flat MPI mode, as it is currently written. If I do this I would like to think about doing it in the next programming model of PETSc (pthreads?). Anyway, this would take enough work that I'd like to think a bit about its design and even the algorithm in a non flat MPI model. Note, I see the win with G-S over Cheby in highly unsymmetric (convection, hyperbolic) problems where Cheby is not very good. Mark -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20111223/fb894a14/attachment.html>
