[petsc-dev] getting processor for off proc value

[Jed Brown]

On Fri, Jul 8, 2011 at 16:40, Barry Smith <bsmith at mcs.anl.gov> wrote:

> Are we planning on making the VecScatter the communications central for
> PETSc?
>

What about moving integer data over the same pipes? I'm not sure it needs to
be that complicated since it should be basically only a difference in the
packing.


>     I can add a VecScatterGetFromRank()  (ugly name) that returns the rank
> for each received entry; there might be enough information to do this
> without any additional communication.  There could also be a
> VecScatterGetToRank() (ugly name) indicating the process to whom we are
> sending data. Etc etc.
>

If we could move integer data with VecScatter, then I wouldn't be so worried
about these more specific queries because the cost to construct the
VecScatter is already a bit higher than one execution of VecScatter to
deliver these ranks or whatever else.

Saving the IS used to create the VecScatter seems useful, especially if we
go implement the VecScatterMerge() that we discussed earlier (to increase
the communication granularity for DMComposite and similar).
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