[Mpi-forum] [EXTERNAL] Wording in MPI standard
wgropp at illinois.edu
Tue Nov 27 09:36:53 CST 2012
I agree that a general cleanup of the standard to conform to established practice would be best. We tried to do that with removing the "legal/illegal" statements and correcting them to valid/invalid.
Director, Parallel Computing Institute
Deputy Director for Research
Institute for Advanced Computing Applications and Technologies
Paul and Cynthia Saylor Professor of Computer Science
University of Illinois Urbana-Champaign
On Nov 27, 2012, at 9:34 AM, Jeff Squyres wrote:
> I think we've done that kind of thing before (i.e., put a blanket statement in the T&C chapter, instead of fixing every individual instance).
> Do we want to take an approach like that here? Or do we want to grep/examine each instance of "should" in the standard?
> I think the latter would be better, but recognize that it would be a fair amount of work (that I'm not volunteering to do).
> On Nov 27, 2012, at 10:15 AM, Jeff Hammond wrote:
>> There's a lot of ambiguity in the definitions of these words in
>> different contexts. If the MPI Forum wants "should" to mean "is
>> required to", then such a definition should be explicit in the text.
>>> From http://en.wikipedia.org/wiki/Shall_and_will#Technical_specifications:
>> "The IETF (Internet Engineering Task Force) defines shall and must as
>> synonymous terms denoting absolute requirements, and should as
>> denoting a somewhat flexible requirement, in RFC documents."
>> On Tue, Nov 27, 2012 at 9:48 AM, Rajeev Thakur <thakur at mcs.anl.gov> wrote:
>>> If you search for the word "should" in the document, it is used all over the place. And it does not mean "maybe"
>>> On Nov 27, 2012, at 8:23 AM, Pavan Balaji wrote:
>>>> On 11/27/2012 04:48 AM US Central Time, Jeff Hammond wrote:
>>>>> Is it explicitly defined anywhere that "foo has been started" means
>>>>> "MPI_I*foo has been called by the appropriate MPI rank" or "sufficient
>>>>> matching has occurred such that foo can proceed without additional
>>>>> explicit remote activity"? Perhaps this text would be more clear if
>>>>> it were more pedantic in this respect, assuming either of my
>>>>> equivalences are correct.
>>>> I think this needs to be clarified -- I always tell people that it needs
>>>> to be matched (even though the standard says it should have "started" --
>>>> what does that mean, if matching has started, but not completed, is it
>>>> considered "started").
>>>>> As for language, while "should" isn't legally enforceable in the same
>>>>> way that "must" or "shall" are, the MPI standard is not a legally
>>>>> binding document and I don't think any MPI implementer wants to be
>>>>> known as the jerk that exploits this loophole to create a formally
>>>>> standard-compliant implementation that screws over users by violating
>>>>> the principle of least surprise in important use cases such as Scott's
>>>> I have to agree with Scott here -- "must" or "is required to be" is a
>>>> clearer way to describe it.
>>>> -- Pavan
>>>> Pavan Balaji
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>> Jeff Hammond
>> Argonne Leadership Computing Facility
>> University of Chicago Computation Institute
>> jhammond at alcf.anl.gov / (630) 252-5381
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> Jeff Squyres
> jsquyres at cisco.com
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