[Mpi-forum] [EXTERNAL] Wording in MPI standard

[Jeff Hammond]

> 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?

This is the safer route.  It's possible, if not likely, that some
chapter authors have used "should" in the sense of "you should brush
your teeth every night" rather than "you should avoid pedestrians
while driving."

> 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).

I will see how far I get on this before next week.

Jeff

> 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."
>>
>> Jeff
>>
>> 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"
>>> http://dictionary.reference.com/browse/should?s=t
>>>
>>> Rajeev
>>>
>>> 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
>>>>> example.
>>>>
>>>> I have to agree with Scott here -- "must" or "is required to be" is a
>>>> clearer way to describe it.
>>>>
>>>> -- Pavan
>>>>
>>>> --
>>>> Pavan Balaji
>>>> http://www.mcs.anl.gov/~balaji
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>>>
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>>
>>
>> --
>> Jeff Hammond
>> Argonne Leadership Computing Facility
>> University of Chicago Computation Institute
>> jhammond at alcf.anl.gov / (630) 252-5381
>> http://www.linkedin.com/in/jeffhammond
>> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond
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>
> --
> Jeff Squyres
> jsquyres at cisco.com
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-- 
Jeff Hammond
Argonne Leadership Computing Facility
University of Chicago Computation Institute
jhammond at alcf.anl.gov / (630) 252-5381
http://www.linkedin.com/in/jeffhammond
https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond