[Mpi-comments] One comment on MPI-3.0 Draft 2, August 2012

[Sébastien Boisvert]

Dear MPI Forum committee members,

I would like to submit a comment on the MPI-3.0 Draft 2, August 2012
for your consideration.

Version: MPI-3.0 Draft 2, August 2012.

The URL of the version of the MPI standard:
http://meetings.mpi-forum.org/draft_standard/mpi3.0_draft_2.pdf

Page: 65

Line number: 28

Section: 3.8.1

In: 

3. Point-to-Point Communication
     3.8 Probe and Cancel
           3.8.1 Probe

Comment:

It says that the source argument of MPI_Iprobe can be MPI_ANY_SOURCE, but it
does say anything about fairness. Therefore MPI_ANY_SOURCE can lead to resource
starvation.

I think it would be better if probing would be done in a round-robin fashion
when the source is MPI_ANY_SOURCE so that any MPI rank has an equal chance of
having its message probed and received.

Presently, the MPI standard contains nothing about which source should be probed when
MPI_ANY_SOURCE is provided.

I hope you will consider my comment.


Sincerely,


Sébastien Boisvert
PhD student
Université Laval