[mpi-21] Ballot 4 - Re: Request for interpretation

Thu Jan 31 08:20:24 CST 2008

Jim -

I was taking the view that the description of what to do for a recognized
key but dubious value belongs to the function that  recognizes the specific
key.  For example if MPI_File_open accepts a "buffer_size" hint with range
"32K" to "16M" we may want to define the behavior of hints that are out of
range.

Once we say an info can have arbitrary keys we need to state that every
info consumer must be prepared to ignore keys it does not recognize because
we have made unrecognizable keys legitimate.

             Dick
Dick Treumann  -  MPI Team/TCEM
IBM Systems & Technology Group
Dept 0lva / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
Tele (845) 433-7846         Fax (845) 433-8363

mpi-21-bounces_at_[hidden] wrote on 01/31/2008 08:43:04 AM:

> However, you have apparently lost the liberty to have undefined
> behavior which was there in the previous version.
>
> Maybe you should keep that, something like
> An implementation must support info objects as caches for arbitrary
> (key, value) pairs, regardless of whether it recognizes the keys.
> Each MPI function which takes hints in the form of an MPI_Info must
> be prepared to ignore any key it does not recognize. However if a
> function recognizes a key but not the associated value, then the
> behavior is undefined.
> (Modifications in italics)
> -- Jim
>
> James Cownie <james.h.cownie_at_[hidden]>
> SSG/DPD/PAT
> Tel: +44 117 9071438
>
> From: mpi-21-bounces_at_[hidden] [mailto:mpi-21-bounces_at_[hidden]]
> On Behalf Of Richard Treumann
> Sent: 31 January 2008 13:29
> To: Mailing list for discussion of MPI 2.1
> Subject: Re: [mpi-21] Ballot 4 - Re: Request for interpretation
>
> Your wording works for me Rolf. -- Thanks
>
>
> Dick Treumann - MPI Team/TCEM
> IBM Systems & Technology Group
> Dept 0lva / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
> Tele (845) 433-7846 Fax (845) 433-8363
>
>
> mpi-21-bounces_at_[hidden] wrote on 01/31/2008 05:25:46 AM:
>
> > I try to summarize all 3 replies in one proposal:
> >
> > ___________________________________
> >
> > Proposal:
> > MPI 2.0, Sect. 4.10 Info Objects, page 43, line 38-40 read:
> >    If a function does not recognize a key,
> >    it will ignore it, unless otherwise specified.
> >    If an implementation recognizes a key but does not recognize
> >    the format of the corresponding value, the result is undefined.
> > but should read:
> >    An implementation must support info objects as caches for arbitrary
> >    (key, value) pairs, regardless of whether it recognizes the pairs.
> >    Each MPI function which takes hints in the form of an MPI_Info must
> >    be prepared to ignore any key it does not recognize.
> >
> > Add after MPI 2.0, Sect. 4.10 Info Objects, page 44, line 22 a new
> > paragraph:
> >    Advice to implementors.
> >    Although in MPI functions that take hints in form of an MPI_Info
> >    (e.g., in process creation and management, one-sided communication,
> >    or parallel file I/O), an implementation must be prepared to ignore
> >    keys that it does not recognize, for the purpose of
MPI_INFO_GET_NKEYS,
> >    MPI_INFO_GET_NTHKEY, MPI_INFO_GET_VALUELEN, and MPI_INFO_GET, the
> >    implementation must retain all (key,value) pairs so that layered
> >    functionality can also use the Info object.
> >    (End of advice to implementors.)
> > _____________________________
> > Rationale for this clarification:
> >
> >    The MPI-2.0 text allowed that also MPI_INFO_DELETE, MPI_INFO_SET,
> >    MPI_INFO_GET, and MPI_INFO_DUP could ignore (key,value) pairs
> >    that are not recognized in routines in other chapters that
> >    take hints with info arguments.
> >    The proposed clarification is necessary when we assume, that
> >    layered implementation of parts of the MPI-2 standard should
> >    be possible and may use the MPI_Info objects for their needs.
> >    This was a goal of the MPI-2 Forum and the MPI-2.0 specification.
> > ___________________________________
> >
> > Bronis, for me, your wording "an MPI implementation may restrict" was
> > in conflict with the rest of the advice. I hope the formulation above
> > is also okay. It is based on the new wording from you and Dick in first

> > part of the proposal.
> >
> > Best regards
> > Rolf
> >
> >
> > Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner_at_[hidden]
> > High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530
> > University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832
> > Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner
> > Nobelstr. 19, D-70550 Stuttgart, Germany . (Office: Allmandring 30)
> > _______________________________________________
> > mpi-21 mailing list
> > mpi-21_at_[hidden]
> > http://lists.cs.uiuc.edu/mailman/listinfo/mpi-21
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