[petsc-dev] programming model for PETSc

[Dmitry Karpeev]

So then are you planning to re-engineer PetscLayout?
Or is it acceptable to have a few PetscLayouts, in their current form,
lying around?

On Thu, Nov 24, 2011 at 6:14 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> On Thu, Nov 24, 2011 at 18:05, Dmitry Karpeev <karpeev at mcs.anl.gov> wrote:
>
>> Is O(commSize) storage considered unscalable in this model?
>
>
> I would like to avoid it where possible. If we have million-way
> parallelism at the network level (e.g. one million MPI processes), then we
> have to justify the memory usage. One 64-bit integer per process is 8MB. If
> that is needed once for the entire application, it is probably not an
> issue, but if it's needed by every object, then it could add up to a
> substantial amount (considering the low-memory estimates).
>
> The MPICH guys are thinking about this:
>
> http://www.mcs.anl.gov/~goodell/pdfs/mpi-mem-final.pdf
>
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