[Mpi3-rma] Conflicting accesses

[William Gropp]

I agree that this example should work.

Bill

On Dec 11, 2010, at 6:50 PM, Torsten Hoefler wrote:

> Hi all,
>
> We discussed the issue with the lockall/shared mode that the outcome  
> of
> overlapping puts or put/get will be undefined. Our discussion ended  
> at a
> point where we believed that such accesses are not valid in
> lockall/shared because there is only one access/exposure epoch.
>
> The statement (not in MPI-2) at the end of page 42 seems to imply  
> that.
> However, I don't think that anything on page 10 (the rules for
> conflicting accesses) mandate this. Jim created this interesting  
> example
> and both of us think it should be legal to do (without unlocking as  
> was
> required in MPI-2):
>
> lock(exclusive)
> get(tail)
> flush()
> put(tail)
> unlock()
>
> It should be true because flush() implies completion at the target  
> which
> means that the "mini-epoch" is now finished (yes, in MPI-2, we  
> needed to
> close an epoch to get completion, however, in MPI-3 we don't).
>
> Do we all agree? I'd like to remove the sentence starting with "For
> example" on page 42.
>
> All the Best,
>  Torsten
>
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> Torsten Hoefler         | Performance Modeling and Simulation Lead
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William Gropp
Deputy Director for Research
Institute for Advanced Computing Applications and Technologies
Paul and Cynthia Saylor Professor of Computer Science
University of Illinois Urbana-Champaign