[Mpi-forum] Question about MPI_Info set on communicators

[Jeff Squyres (jsquyres)]

-----Original Message-----
From: Jeff Hammond <jeff.science at gmail.com>
Reply: Main MPI Forum mailing list <mpi-forum at lists.mpi-forum.org>
Date: February 16, 2016 at 2:37:57 PM
To: Main MPI Forum mailing list <mpi-forum at lists.mpi-forum.org>
Subject:  Re: [Mpi-forum] Question about MPI_Info set on communicators

> > - "yes" because the user asked for it (i.e., that's the hint, regardless
> > of what the implementation dos with it.
>  
> This answer contradicts the most reasonable interpretation of "hints
> actually used by the system"

See my reply to Jim: if we're supposed to provide the value of *the hint*, that to me sounds like the *user's input* (as opposed to what the system chose to do with that hint).

> > - "no" because the implementation could not provide it
> > - no "foo" key at all because the implementation did not use the hint
>  
> I think these are equivalent from a user perspective. In both cases, the
> user is not getting the "magical_powers"="yes" they requested.
>  
> However, my reading of MPI 3.1 6.4.4 p250 says that the keys should be
> defined, but set to "no".

Ok.

> In any case, we need to improve the standard text unless Bill swoops in to
> tell us we are all idiots and points out text that makes the interpretation
> unambiguous :-)

I agree it needs to be clarified.  It would be nice if we could clarify it in a way that is compatible with the 3.0 and 3.1 text (so that we don't have to have apps distinguish between 3.0/3.1 behavior and beyond-3.1 behavior).

--  
Jeff Squyres
jsquyres at cisco.com  
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