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

[William Gropp]

My recommendation is that the chapter committee fold this into the chapter, rather than add this to the long list of infinitesimal updates.  

Bill

On Feb 13, 2012, at 11:42 AM, Fab Tillier wrote:

> So are we back to needing a ticket for this then?  Or is it still at the discretion of the chapter authors?
> 
> -Fab
> 
> Rolf Rabenseifner wrote on Mon, 13 Feb 2012 at 08:32:07
> 
>> Rajeev and Fab,
>> 
>> yes, you are both right.
>> Then we need a change-log like
>> 
>>>> 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 also a generalized or I/O request is completed.
>> 
>> ----- Original Message -----
>>> From: "Rajeev Thakur" <thakur at mcs.anl.gov> To: "Main MPI Forum mailing
>>> list" <mpi-forum at lists.mpi-forum.org> Sent: Monday, February 13, 2012
>>> 3:32:47 PM Subject: Re: [Mpi-forum] MPI_WAIT/MPI_TEST and generalized,
>>> I/O, and NBC requests 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
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>>>>>>>>>> 
>>>>>>>>>> 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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>>>>>>>> 
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>>>>> 
>>>>> 
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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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>>> 
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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