H5Part development and discussion

[Mark Howison <MHowison AT lbl.gov>]

Hi Andreas,

It means you can have different depths of ghost cells on different
sides of the 3D block. So the top might have +1 ghost cells, but the
sides +2, etc. Adjacent blocks with ghost zones also overlap, and it
is fairly complicated to "reduce" these into non-overlapping regions.
Right now we handle the most general case, where we don't require any
adjacency information from the user. There is an MPI_Allgather where
each processor gets a copy of every other proc's field layout,
requiring O(n) space. Then an O(n^2) algorithm runs redundantly on
each proc to compute the reduction,

It all works and I have never noticed any performance issues
associated with it, but it may become a scalability problem in the
future with say O(100K) or O(1M) cores.

Mark

On Sat, Jul 10, 2010 at 9:23 AM, Andreas Adelmann
<andreas.adelmann AT psi.ch> wrote:
>
>>> Do we need to support arbitrary ghost zones?
>
>
> Sorry I was maybe not following closely: what are rbitrary ghost zones 
> w.r.t. H5Block?
>
> AA