On Sat, 27 Oct 2012, Derek Gaston wrote:
> We actually don't compute off-processor extra sparsity entries
> currently. We do all the work to get all the info on the local
> processor that the local processor needs to make decisions about
> it's sparsity pattern and then just add the local entries.
Really? That can be hard as hell. I wrote this communication code
because I hit a case where DoF A on proc X was being contrained
indirectly in terms of DoF B on proc Y, and even after making sure
proc Y and X both knew about the constraint so Y could add the
(B-stencil,A) entries correctly, there was no way to get proc X to add
the corresponding (A,B-stencil) entries, because the elements
supporting B weren't all semilocal on X.
> I might rethink some of that code if there is some new capability now...
Well, let's wait until the new capability is working. ;-) The first
bug I triggered with it turned out to be unrelated and easy-to-fix,
the next one looks to be unrelated and not-too-hard-to-fix, the
threading+MPI bug ought to be tedious-but-easy to fix... but we're
starting to talk about a lot of fixes here.