[Mpi3-ft] Persistent Communication & Sendrecv

[Joshua Hursey]

I was reviewing the point-to-point chapter today looking for wording/interfaces that need to be addressed in the FT proposal. I came across two sets of interfaces that probably deserve to be brought up on the list.

Examples and collective stuff coming soon :)

Persistent Communication:
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https://svn.mpi-forum.org/trac/mpi-forum-web/wiki/ft/run_through_stabilization#a3.9PersistentCommunicationRequests

None of the persistent calls have a 'status' object associated with them, so I had to add some wording about failures during MPI_{*Send|Recv}_init and MPI_Start. The interesting case is if MPI_Startall() fails. What should it return (MPI_ERR_IN_STATUS)? How does an application determine which of the requests:
 - Started
 - Failed
 - Were not started

I think I devised a strategy for the application to check which started and which did not. But I wanted a few more eyes on this to see if there is a better way to deal with this situation.


Sendrecv{_replace}
------------------
https://svn.mpi-forum.org/trac/mpi-forum-web/wiki/ft/run_through_stabilization#a3.10Send-Receive

These interfaces only have one status object associated with them. So if both ranks fail, only one of them can be indicated in the status object. So I wrote up some text to add to this section for the application to determine what happened. Another set of eyes here would be appreciated just to make sure I am not missing anything.


Thanks,
Josh

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Joshua Hursey
Postdoctoral Research Associate
Oak Ridge National Laboratory
http://www.cs.indiana.edu/~jjhursey