[Mpi-forum] MPI_WAIT/MPI_TEST and generalized, I/O, and NBC requests

[Rajeev Thakur]

Nonblocking *independent* I/O requests existed in MPI-2. Nonblocking collective I/O may come in MPI-3.

Rajeev

On Feb 13, 2012, at 7:20 AM, Rolf Rabenseifner wrote:

>> Non-blocking I/O requests weren't covered by the text in the 2.2
>> standard, so it's not just generalized requests that were missed.
> 
> Non-blocking I/O requests did not exist in MPI-2.2. 
> They may come with MPI-3.0.
> 
> Yes, your text is perfect.
> Do you file the ticket?
> Please use official MPI-2.2 page and line numbers,
> as in nearly all other tickets.
> I would say, it is enough when you copy the paragraphes
> mentioned in may email into the ticket.
> 
> As Change-log, I would recommend:
> 
> Section 3.7 on page 48.[[BR]]
> It is clarified that MPI_Wait and MPI_Test set the request handle to
> MPI_REQUEST_NULL if a generalized request is completed.
> 
> Best regards
> Rolf
> 
> 
> ----- Original Message -----
>> From: "Fab Tillier" <ftillier at microsoft.com>
>> To: "Main MPI Forum mailing list" <mpi-forum at lists.mpi-forum.org>
>> Sent: Monday, February 13, 2012 12:45:13 AM
>> Subject: Re: [Mpi-forum] MPI_WAIT/MPI_TEST and generalized, I/O, and NBC requests
>> 
>> Non-blocking I/O requests weren't covered by the text in the 2.2
>> standard, so it's not just generalized requests that were missed.
>> Other than that, you have it correct Rolf. I would word it slightly
>> differently, though, something along the lines of:
>> 
>> "If the operation associated with this request was a persistent
>> communication operation, the persistent communication request is
>> marked as inactive. Other nonblocking operations are deallocated and
>> the request handle is set to MPI_REQUEST_NULL."
>> 
>> Basically, mention the special case of persistent requests first, so
>> as to avoid the negative (non-persistent requests).
>> 
>> -Fab
>> 
>> Rolf Rabenseifner wrote on Sun, 12 Feb 2012 at 05:46:17
>> 
>>> When I understand correctly, then we have two problems:
>>> 
>>> 1. MPI-2.2 has the "bug" that MPI-2.2
>>>   page 53 line 47 - page 54 line 3, and page 54 lines 40-45
>>>   do not mention the generalize requests although it was intended
>>>   that MPI_Wait or MPI_Test of a generalized request acts
>>>   as it would have been a isend or irecv request.
>>> 2. Nobody has checked for nonblocking collectives and
>>>   nonblocking I/O that this text must now also include those
>>>   routines.
>>> When I also understand correctly, then we currently say
>>> 
>>>  "If the communication object associated with this request
>>>   was created by a nonblocking send or receive all,
>>>   then ..."
>>> but we wanted to say
>>> 
>>>  "If the communication object associated with this request
>>>   is not a persistent communication request (see Section 3.9 on
>>>   page 69),
>>>   then ..."
>>> Yes?
>>> 
>>> This change would solve both problems. Yes?
>>> 
>>> Best regards
>>> Rolf
>>> 
>>> 
>>> ----- Original Message -----
>>>> From: "Bronis R. de Supinski" <bronis at llnl.gov> To: "Fab Tillier"
>>>> <ftillier at microsoft.com> Cc: "Main MPI Forum mailing list"
>>>> <mpi-forum at lists.mpi-forum.org> Sent: Saturday, February 11, 2012
>>>> 7:57:30 PM Subject: Re: [Mpi-forum] MPI_WAIT/MPI_TEST and
>>>> generalized,
>>>> I/O, and NBC requests I will leave it to you to decide. I am sure I
>>>> will be very pressed for time...
>>>> 
>>>> On Sat, 11 Feb 2012, Fab Tillier wrote:
>>>> 
>>>>> I think it would make more sense to fix the text for the WAIT and
>>>>> TEST routines, rather than spread the information around. The
>>>>> generalized request section might not need changes if we do this.
>>>>> 
>>>>> I don't know if I'll have time to put the text together before the
>>>>> meeting, though.
>>>>> 
>>>>> -Fab
>>>>> 
>>>>> Bronis R. de Supinski wrote on Sat, 11 Feb 2012 at 10:13:48
>>>>> 
>>>>>> 
>>>>>> I am fine with the decision to make it the chapter committee
>>>>>> responsibility. I suppose that means I need to draft text
>>>>>> for the generalized requests?
>>>>>> 
>>>>>> On Sat, 11 Feb 2012, William Gropp wrote:
>>>>>> 
>>>>>>> It looks like this is a result of adding new request types
>>>>>>> without
>>>>>>> revisiting
>>>>>>> the original text. Under generalized requests, there is text
>>>>>>> that
>>>>>>> seems to
>>>>>>> imply that the request is set to MPI_REQUEST_NULL on completion,
>>>>>>> but it
>>>>>>> isn't explicit and should be.
>>>>>>> 
>>>>>>> This is a chapter committee correction.
>>>>>>> 
>>>>>>> Bill
>>>>>>> 
>>>>>>> On Feb 10, 2012, at 6:04 PM, Fab Tillier wrote:
>>>>>>> 
>>>>>>> Hi Folks,
>>>>>>> 
>>>>>>> Looking at the text for MPI_WAIT (page 54, line 15) and MPI_TEST
>>>>>>> (page 55,
>>>>>>> line 7), it seems to imply that the request handle is only set
>>>>>>> to
>>>>>>> MPI_REQUEST_NULL for non-blocking send and receive requests. Are
>>>>>>> generalized, I/O, and NBC requests not completed the same way?
>>>>>>> Are
>>>>>>> users
>>>>>>> required to free such requests explicitly after they complete
>>>>>>> using
>>>>>>> MPI_REQUEST_FREE?
>>>>>>> 
>>>>>>> I would have expected that all request handles except those to
>>>>>>> persistent
>>>>>>> requests are set to MPI_REQUEST_NULL, and persistent request
>>>>>>> just
>>>>>>> rather
>>>>>>> marked inactive. If that is indeed the intent, shouldn't we
>>>>>>> update
>>>>>>> the text to
>>>>>>> reflect this? Is this a ticket-0 level change?
>>>>>>> 
>>>>>>> Thanks,
>>>>>>> -Fab
>>>>>>> 
>>>>>>> 
>>>>>>> _______________________________________________ mpi-forum
>>>>>>> mailing
>>>>>>> list mpi-forum at lists.mpi-forum.org<mailto:mpi-forum at lists.mpi-
>>>>>>> forum.org>
>>>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-forum
>>>>>>> 
>>>>>>> William Gropp
>>>>>>> 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
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
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> 
> -- 
> 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: Allmandring 30)
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