Jed Brown jed at 59A2.org
Tue Dec 7 13:30:51 CST 2010

On Tue, Dec 7, 2010 at 20:21, Ethan Coon <ecoon at lanl.gov> wrote:

> 'd like a DA where there are ghost cells on every boundary, and some of
> those ghost cells (but not all) are filled in with periodic values.

It would be useful to people doing explicit stuff if there was a way to get
ghost nodes in the local vector without implying periodic communication (and
weird coordinate management).

A related issue for purely explicit is to have a way to VecAXPY without
needing to copy to and from a global vector.  (TSSSP has low-memory schemes,
paying for an extra vector or two is actually significant in that context,
and (less significant) I'm certain I can cook up a realistic benchmark where
the memcpy costs more than 10%.)  I think I know how to implement this
sharing transparently (more-or-less using VecNest) so we could make it
non-default but be able to activate it at runtime.

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