On Mon, Jan 7, 2013 at 8:12 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> > On Jan 7, 2013, at 8:05 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote: > > > It's sort of awkward to deal with PCREDUNDANT for coarse grids, and I > have yet to see any evidence that it's better than gathering to rank 0, > solving sequentially, and scattering the result. What about implementing LU > for MPIAIJ to do the latter algorithm? Then we could trivially make it > smart enough to skip the gather when Mark uses it on the coarse grid of > GAMG (where the entire system is already on rank 0). In additon to being > simpler for the user to interact with, this would fix a lot of fighting > between the PCMG and its children. > > I thought PCREDUNDANT had this ability? What about adding it? That wouldn't be redundant at all, so if we put it there, we'd have to at least rename it. > Have an option that cause PCREDUNDANT to only collect a single copy of the > matrix from rank 0 to r-1 and in your case r is 1. I hate the idea of > having another separate place with similar stuff to PCREDUNDANT. You could > then implement LU for MPIAIJ using this variant of PCREDUNDANT, that is a > call to PCREDUNDANT stuff with the right options. > > Barry > > > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20130107/5a7614f2/attachment.html>
