[mpiwg-rma] Proposed Info Key

Jeff Hammond jeff.science at gmail.com
Tue Oct 14 10:58:07 CDT 2014

Thanks, Pavan, for sharing the details.  I forgot about the MPICH info
key used here.

Now that I understand the issue, I think we should pursue both
tickets, especially since my ticket is definitely 4.0 material.
Standardizing the info key that makes the MPICH solution portable in
the 3.1 timeframe is a good idea.

And I should note that this is not only an academic problem - there
are a number of projects making use of the (ppn+1)-windows trick
already and will benefit from the info key Mikhail proposed.


On Tue, Oct 14, 2014 at 8:54 AM, Balaji, Pavan <balaji at anl.gov> wrote:
> On Oct 14, 2014, at 10:43 AM, Jim Dinan <james.dinan at gmail.com> wrote:
>> IIUC, MPICH has started detecting this automatically without the info key, so this ticket may be moot.  Hopefully an MPICH developer familiar with this optimization can comment.
> Yes, but we rely on an internal info key as well in order to avoid the search time.  Though I think we can optimize this search with an AVL tree or something.
> Note that Jeff’s ticket gives more capability that this — it allows the user to do load/store accesses.  Your info key only allows the MPI implementation to internally optimize communication.
>   — Pavan
> --
> Pavan Balaji  ✉️
> http://www.mcs.anl.gov/~balaji
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Jeff Hammond
jeff.science at gmail.com

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