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

Jim Dinan dinan at mcs.anl.gov
Wed Dec 7 13:57:00 CST 2011

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:



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
>> _______________________________________________
>> mpi-forum mailing list
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