[mpi3-coll] [MPI Forum] Ticket #168 MPI_Icomm_dup

James Dinan dinan at mcs.anl.gov
Mon Nov 21 17:49:49 CST 2011

Hi Torsten,

I have a couple questions about this proposal:

Why MPI_Icomm_dup() and not MPI_Icomm_create()?  It seems like 
MPI_Icomm_create would be more general while still providing the same 

Why is this crucial for nonblocking libraries?  It seems like a 
synchronous initialization routine for such a library should be 
sufficient from a functionality point of view.  Is this primarily a 
performance argument?  Maybe you can point me to a specific passage in 
the paper?


On 11/13/11 9:25 AM, Torsten Hoefler wrote:
> Hi Collective WG members and "Groups, Contexts, and Communicators" Committee,
> We discussed the functionality of a nonblocking communicator duplication
> during MPI-2.2 and deferred the ticket (#164) to MPI-3 because we didn't
> want to add too much at that point.
> This functionality is crucial for the implementation of nonblocking
> libraries (and the library concept in general) in MPI. For a detailed
> discussion see Hoefler, Snir: "Writing Parallel Libraries with MPI -
> Common Practice, Issues, and Extensions".
> I beefed up the ticket to make it a full MPI-3 ticket and I would like
> to have a reading at the January meeting. Everybody who is in the "To"
> field of this message, please review this ticket in the context of the
> groups and communicators and collectives chapters and comment (also
> indicate when it's ok). Everybody else on the ML is invited to review
> too.
> The collective operations and topologies WG will have another telecon
> where this ticket is discussed soon.
> Thanks&  Best,
>    Torsten
> PS: please check if I got your username in the CC field right, and
> correct it if it is wrong (I didn't find an index for those).

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