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

Tue Feb 14 02:57:01 CST 2012

A change that needs a change-log entry is not a ticket-0
change. Therefore a ticket with ticket number is needed and
it should be done now, added to the agenda, and read in Chicago.

This change definitely is a correction that changes
the standard, but hopefully no implementation,
because all existing implementations may have
it already implemented (i.e. are currently wrong 
if we look at the wording of MPI-2.2).

Because it is very clear, it should need only 10 minutes
of the Forum time.

Rolf

----- Original Message -----
> From: "William Gropp" <wgropp at illinois.edu>
> To: "Main MPI Forum mailing list" <mpi-forum at lists.mpi-forum.org>
> Sent: Monday, February 13, 2012 7:38:16 PM
> Subject: Re: [Mpi-forum] MPI_WAIT/MPI_TEST and generalized, I/O, and NBC requests
> 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
> >>>>>>>>>> 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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> >>>>>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-forum
> >>>>>>>>
> >>>>>>>>
> >>>>>>> _______________________________________________
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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)
> >>>> _______________________________________________
> >>>> mpi-forum mailing list
> >>>> mpi-forum at lists.mpi-forum.org
> >>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-forum
> >>>
> >>>
> >>> _______________________________________________
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> >>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-forum
> >>
> >
> >
> > _______________________________________________
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> > 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)