[mpi3-coll] [Mpi-forum] MPI_Comm_create_group Meeting

Jim Dinan dinan at mcs.anl.gov
Thu Dec 8 10:41:00 CST 2011


Hi Bronis,

Thanks very much for the feedback.  I've created a ticket (#305) with 
some initial text for MPI_Intercomm_create:

https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/305

I updated the MPI_Comm_create_group text with your corrections and also 
made some additional updates to the tags paragraph (page 228, line 12) 
to hopefully address a few other questions I got off-list.  A new PDF is 
attached.  I'd appreciate a second look if you have time.

Thanks,
  ~Jim.

On 12/7/11 9:00 PM, Bronis R. de Supinski wrote:
>
> Jim:
>
> I think it would be good to create a companion ticket to make
> MPI_Intercomm_create use the tag space. We should get that
> ticket ready now (I expect it is just a few lines of change)
> so that it will be in MPI 3.0, assuming ticket 286 passes.
>
> Anyway, please change:
>
> "new intracommunicator, newcomm, whose communication group is defined by
> the group argument."
>
> to:
>
> "new intracommunicator, newcomm, for which the group argument defines
> the communication group."
>
> Also, please change:
>
> "to order calls and/or use different tag arguments"
>
> to
>
> "to order calls and/or to use differenttag arguments"
>
> Bronis
>
>
>
> On Wed, 7 Dec 2011, Jim Dinan wrote:
>
>> Hi All,
>>
>> I've updated the text with feedback from the last meeting, adding text
>> to define a collective tag space. Please take a look at the ticket286
>> edits in the attached PDF and send any feedback.
>>
>> Also, I'd like to have another conference call early next week to
>> discuss and get ready for a reading in January. Please fill in your
>> availability on the doodle poll:
>>
>> http://www.doodle.com/yx5b2f5f5hwc2qzq
>>
>> Thanks,
>> ~Jim.
>>
>> On 11/8/11 3:57 PM, James Dinan wrote:
>>> Hi All,
>>>
>>> Notes from yesterday's meeting are attached. Please note that we are
>>> moving all future discussion of this ticket to the mpi3-coll mailing
>>> list.
>>>
>>> Best,
>>> ~Jim.
>>>
>>> In attendance:
>>>
>>> Adam Moody, David Goodell, Jim Dinan, Pavan Balaji, Fab Tiller, Bronis
>>> de Supinski, Jeff Hammond
>>>
>>> Item 1: Name of the routine.
>>>
>>> We decided to stick with MPI_Comm_create group as the best way of
>>> matching the MPI_CLASS_ACTION_SUBSET naming convention.
>>>
>>> Item 2: Tag versus color.
>>>
>>> We decided to use a tag, which is defined to be in a collective tag
>>> space that is distinct from the point-to-point tag space. The collective
>>> tag will follow all MPI tag semantics, however it will not conflict with
>>> any point-to-point tags (including MPI_ANY_TAG). This essentially
>>> exposes the expected implementation in the standard, providing more
>>> flexible semantics to the user. In addition, it allows an implementation
>>> to make more efficient use of the tag space by defining tag conflicts
>>> across tagged collective operations (currently only MPI_Intercomm_create
>>> and MPI_Comm_create_group, but we could define others in the future).
>>>
>>> In a separate ticket, we can update MPI_Intercomm_create to specify that
>>> its tag is also in the collective tag space. This will be backward
>>> compatible, but will make MPI_Intercomm_create considerably easier to
>>> use because its tags will no longer conflict with point-to-point
>>> operations.
>>>
>>> Tasks:
>>>
>>> * Jim will work on a revision of the text that follows the above
>>> semantics.
>>>
>>> * The group will reconvene after Thanksgiving to review new text.
>>>
>>> * The group will move discussion to the collectives mailing list.
>>>
>>>
>>> On 11/4/11 11:07 AM, James Dinan wrote:
>>>> Based on the doodle poll, it looks like Monday at 3pm CT will be the
>>>> best time to meet. We'll use the hybrid WG telecon bridge:
>>>>
>>>> Domestic dial number: 866-654-6744
>>>> International dial number: 517-308-8226
>>>> Passcode: 6086006
>>>>
>>>> See you then,
>>>> ~Jim.
>>>>
>>>> On 11/1/11 2:33 PM, James Dinan wrote:
>>>>> Hi All,
>>>>>
>>>>> I would like to form a group to review the MPI_Comm_create_group()
>>>>> proposal (#286) for a formal reading at the next Forum meeting. If you
>>>>> are interested in joining the discussion, could you please fill in
>>>>> your
>>>>> availability for a one hour conference call next week:
>>>>>
>>>>> http://www.doodle.com/9tganzq2hqiqy7kt
>>>>>
>>>>> We have a couple issues to discuss:
>>>>>
>>>>> 1.) The name of the function: MPI_Comm_create_group,
>>>>> MPI_Group_comm_create, MPI_Comm_create_from_group, ...
>>>>>
>>>>> 2.) The tag argument: Should we use a tag or a "color" to establish a
>>>>> safe communication conduit on the parent communicator. As discussed at
>>>>> the Forum, using a tag could conflict with the use of MPI_ANY_TAG
>>>>> on the
>>>>> parent communicator. A color would avoid this issue, however it could
>>>>> complicate tag matching.
>>>>>
>>>>> 3.) Changes to the text.
>>>>>
>>>>> Thanks,
>>>>> ~Jim.
>>>>>
>>>>> PS- I've attached a copy of the current text with comments from the
>>>>> formal reading at the last Forum meeting (in Acrobat: Comments ->
>>>>> Comments View -> Show Comments List for the full list).
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> 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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>>
>
>
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