[mpiwg-tools] [MPIWG Fortran] Proposal: MPI_SIZEOF not profiled

Mon May 19 13:19:58 CDT 2014

Ok.  Will any other Fortran people be there?  (besides me)

On May 19, 2014, at 2:03 PM, Martin Schulz <schulzm at llnl.gov> wrote:

> Yes, sounds like it - I¹ll take 428 off the list then. We should take some
> time on Monday afternoon as part of the tools WG time to talk about this.
> 
> Martin
> 
> ________________________________________________________________________
> Martin Schulz, schulzm at llnl.gov, http://scalability.llnl.gov/
> CASC @ Lawrence Livermore National Laboratory, Livermore, USA
> 
> 
> 
> 
> 
> 
> 
> 
> On 5/19/14, 8:35 AM, "Jeff Squyres (jsquyres)" <jsquyres at cisco.com> wrote:
> 
>> I think we need to push this errata out to the Japan meeting.  There
>> seems to be a bunch of subtlety here; trying to rush this through today
>> does not seem like a good idea just to meet the T-2 week deadline for the
>> Chicago meeting (which technically expires at 2pm US Central time today
>> -- which is about 3.5 hours from now).
>> 
>> Let me try to summarize the salient points so far:
>> 
>> 1. The old text kinda sucks:
>>  a. it says "macros" (including the section title) where it really
>> means "not interceptable"
>>  b. p19 implies that these function can only be macros in C (not
>> inlined, and not in Fortran), which seems to contradict p555
>> 
>> 2. We need to add the Status conversion functions in there
>> 
>> 3. We want to add MPI_SIZEOF (which is Fortran-only, BTW) to the list
>> 
>> 4. The use of the word "inline" seems to be a bad idea because it can
>> have many different meanings.  We should say that these functions are not
>> interceptable, which is the real requirement.
>> 
>> 5. I think it would be better to change p555 to not say "macros" (i.e.,
>> "non-interceptable"), but rather to say "the routines listed in 2.6.4"
>> (i.e., who cares what the reason is -- just cite 2.6.4 and let 2.6.4
>> explain everything).
>> 
>> Is that all?
>> 
>> 
>> 
>> 
>> On May 19, 2014, at 11:08 AM, Rolf Rabenseifner <rabenseifner at hlrs.de>
>> wrote:
>> 
>>> Yes, the "allowed as macros" on MPI-3.0 p555:32
>>> would allow a different mechanism for these routines
>>> that makes them non-interceptable.
>>> 
>>> If this "non-interceptable" is done by other means
>>> than macro, then p555:35 "For routines implemented
>>> as macros, it is still required that the PMPI_
>>> version be supplied" would not apply!
>>> 
>>> It is bad to use different wording for having
>>> better English quality ;-(
>>> 
>>> And your are right, my "#ifdef MPI_Wait" says
>>> therefore nothing.
>>> 
>>> Do you all agree that wording in
>>> p19:48 - p20:5 and p555:31-37 is at all inconsistent
>>> and therefore new and useful wording is needed
>>> in this erratum?
>>> 
>>> Rolf 
>>> 
>>> ----- Original Message -----
>>>> From: "N.M. Maclaren" <nmm1 at cam.ac.uk>
>>>> To: "MPI-WG Fortran working group" <mpiwg-fortran at lists.mpi-forum.org>
>>>> Sent: Monday, May 19, 2014 4:35:10 PM
>>>> Subject: Re: [MPIWG Fortran] [mpiwg-tools] Proposal: MPI_SIZEOF not
>>>> profiled
>>>> 
>>>> On May 19 2014, Rolf Rabenseifner wrote:
>>>>> 
>>>>> Bill,
>>>>> 
>>>>> your text goes beyond the errata goal.
>>>>> 
>>>>> The errata goal was:
>>>>> - adding the missing Status conversion
>>>>> - adding MPI_SIZEOF
>>>>> 
>>>>> And this works as errata.
>>>>> 
>>>>> Your goal is to allow also
>>>>> - Fortran non-interceptable for these routines.
>>>>> 
>>>>> Your additional Change is to allow other methods
>>>>> than C macros for C.
>>>>> This would prevent "#ifdef MPI_Wtime".
>>>>> 
>>>>> All this would be MPI-4.0 and not MPI-3.0 errata.
>>>> 
>>>> Would it?  I don't know what useful effect you would expect
>>>> "#ifdef MPI_Wtime" to achieve, but it assuredly would NOT tell
>>>> you (reliably) whether or not it can be accessed through the
>>>> profiling interface.  14.2 says:
>>>> 
>>>>   1. provide a mechanism through which all of the MPI defined
>>>>   functions, except those allowed as macros (See Section 2.6.4),
>>>>   may be accessed with a name shift.
>>>> 
>>>> Because it says "ALLOWED as macros", MPI_Wtime may not be accessed
>>>> through the profiling interface, whether or not it is implemented
>>>> as a macro.  Doing so is a user error, leading to undefined
>>>> behaviour.
>>>> Therefore, an implementation may implement them as C inline
>>>> functions,
>>>> and would meet all of the requirements of MPI.
>>>> 
>>>> The error is more pervasive than just for Fortran.  Because it did
>>>> not say what it meant, but something that was equivalent under K&R C
>>>> (sic), it wasn't strictly true in C90 and was rendered significantly
>>>> misleading (arguably erroneous) by C99.  And that's the reason that
>>>> some people get very unhappy about the proposed partial fix.
>>>> 
>>>> It's also why the best solution is to regard ALL of the wording as
>>>> an error - which would probably mean starting a new ticket.  But it's
>>>> definitely an error in the wording, not a change.
>>>> 
>>>> 
>>>> Regards,
>>>> Nick Maclaren.
>>>> 
>>>> _______________________________________________
>>>> mpiwg-fortran mailing list
>>>> mpiwg-fortran at lists.mpi-forum.org
>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran
>>>> 
>>> 
>>> -- 
>>> Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner at hlrs.de
>>> 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: Room 1.307)
>>> _______________________________________________
>>> mpiwg-fortran mailing list
>>> mpiwg-fortran at lists.mpi-forum.org
>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran
>> 
>> 
>> -- 
>> Jeff Squyres
>> jsquyres at cisco.com
>> For corporate legal information go to:
>> http://www.cisco.com/web/about/doing_business/legal/cri/
>> 
>> _______________________________________________
>> mpiwg-tools mailing list
>> mpiwg-tools at lists.mpi-forum.org
>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-tools
> 
> 
> _______________________________________________
> mpiwg-fortran mailing list
> mpiwg-fortran at lists.mpi-forum.org
> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran

-- 
Jeff Squyres
jsquyres at cisco.com
For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/