[Mpi-forum] MPI "Allocate receive" proposal

[Dries Kimpe]

* Anthony Skjellum <tony at cis.uab.edu> [2013-08-26 14:29:01]:

> If I understand this correctly, some of us suggested allocate-on-receive, free-on-send mode,
> but left this out in MPI-1.  I advocated this type of reactive semantics ... That's how
> the Reactive Kernel worked at Caltech for instance...  Allowing for MPI to choose efficient memory for messages of some sizes
> can provide nice properties, provided the memory is good to compute in.  There are always concerns about starvation from holding
> the messages too long :-)  

> I'd like to see this get full consideration.  It could be a big help in exascale to have fine-grain computing.

> For instance, could we not get zero-copy unexpected short messages in this way?

Don't forget to consider one-sided communication. Many of the proposed
uses for MPI_Arecv could be implemented using one-sided, given some more
application knowledge (which the application programmer has).

For example, implementing zero-copy unexpected short messages is pretty
trivial using the newer one-sided functions.

  Dries
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