[mpi-21] MPI_GET_PROCESSOR_NAME Fortran and C

[Rolf Rabenseifner]

Dick,

your right and it is already decided:
MPI 1.1 Sect. 7.1 page 193, lines 13-14:
  "This routine returns the name of the processor on which it 
  was called at the moment of the call."
And lines 22-25:
  "Rationale. This function allows MPI implementations that do 
  process migration to return the current processor. Note that 
  nothing in MPI requires or defines process migration; this 
  definition of MPI GET PROCESSOR NAME simply allows such 
  an implementation. (End of rationale.)"

I.e., current location, i.e., it may change in case of 
check point/restart and all the other reasons you mentioned.

I would say, that the sentences above are clear enough.

Okay?

Best regards
Rolf

On Fri, 25 Jan 2008 15:32:07 -0500
 Richard Treumann <treumann_at_[hidden]> wrote:
>We also should decide whether every call to MPI_GET_PROCESSOR_NAME across
>the life of the task must return the same name.  On very large machines
>running very large jobs, migration of some tasks off of failing nodes and
>on to robust nodes will become more interesting. Checkpoint/restart raises
>the same issue.  A restarted job will probably not have the same task to
>node mapping.
>
>We can either require the name to remain constant and allow that it might
>be a "virtual" name or require that it return an "actual" name but allow it
>to change.
>
>               Dick
>
>Dick Treumann  -  MPI Team/TCEM
>IBM Systems & Technology Group
>Dept 0lva / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
>Tele (845) 433-7846         Fax (845) 433-8363
>
>
>mpi-21-bounces_at_[hidden] wrote on 01/25/2008 12:00:42 PM:
>
>> This is a discussion-point for MPI 2.1, Ballot 4.
>>
>> This is a follow up to:
>>   MPI_GET_PROCESSOR_NAME and Fortran
>>   in http://www.cs.uiuc.edu/homes/wgropp/projects/parallel/MPI/mpi-
>> errata/index.html
>> with mail discussion in
>>   http://www.cs.uiuc.edu/homes/wgropp/projects/parallel/MPI/mpi-
>> errata/discuss/procname/
>>
>> _________________________________________________________________
>>
>> MPI_GET_PROCESSOR_NAME and Fortran
>> and in C and all MPI_xxxx_GET_NAME routines
>> -------------------------------------------
>>
>> Summary: Returning strings is defined in MPI_GET_PROCESSOR_NAME
>> and MPI_xxxx_GET_NAME quite different. Not all implementations
>> are doing the same with zero-filling. And what they do is
>> at least with MPI_GET_PROCESSOR_NAME different to what
>> the current standard requires. A propose to adapt the standard
>> to the common reasonable implementations.
>> The very short proposal for clarification can be found at the
>> end of this text, see C. Proposal.
>>
>> A. MPI_GET_PROCESSOR_NAME
...
>> B. MPI_COMM_GET_NAME (and other MPI_xxxx_GET_NAME)
...
>> C. Proposal:
>> ------------
>>
>> Add the following sentences to the current interface definitions:
>> ------------------
>> In C, a \0 is additionally stored at name[resultlen]. resultlen
>> cannot be larger then MPI_MAX_PROCESSOR_NAME-1
>> (or MPI_MAX_OBJECT_NAME-1). In Fortran, name(resultlen+1:)
>> is filled with spaces. resultlen cannot be larger then
>> MPI_MAX_PROCESSOR_NAME (or MPI_MAX_OBJECT_NAME).
>> ------------------
>>
>> Typo correction:
>> ----------------
>> MPI-1.1 Sect. 7.1, page 193, beginning of line 29 reads
>>    examine the ouput argument
>> But should read (additional t in output)
>>    examine the output argument
>>
>>
>> Okay?
>> _________________________________________________________________
>>
>> Best regards
>> Rolf
>>
>> PS: Attached my tests and short protocols
>>
>>
>>
>> Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner_at_[hidden]
>> 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)
>> [attachment "mpi_get_xxx_name.tar.gz" deleted by Richard
>> Treumann/Poughkeepsie/IBM]
>_______________________________________________
>> mpi-21 mailing list
>> mpi-21_at_[hidden]
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Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner_at_[hidden]
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)