Dear Martyn, Thanks for bringing this up, the Forum appreciates any user input and comments. See my answers below.
Firstly, apologies if this is the wrong place to post - I couldn't see a particularly relevant subgroup or forum for discussion, so if this is the wrong place, redirection is more than welcome.... The right place would probably be the collectives and topology working group, but I think the general forum list is ok as long as the thread does not grow too much.
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As it stands there is no practical way of setting this up - even with the generous support of my vendor. This is in stark contrast to MPI-IO where I have data structures available to pass either vendor specific or generic hints allowing me to modify behaviour on a per-file basis, in application, at runtime. I really want to be able to perform a similar thing when I create communicators, such that when I perform, say, a comm_split, I can create unique characteristics for each of the new communicators. You are correct and this is indeed a missing functionality in MPI-2.2. There is a proposal that allows to attach info objects during communicator duplication (see item #2 "MPI_COMM_DUP_INFO" in https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/271). This has been discussed in the Forum but I don't know the status of this ticket. Adam, can you comment?
So I guess the first question is has any work been taking place in this area, and if not, how do I go about spurring the discussion? Yes, Adam and I worked on this issue a while ago and Adam created the referenced ticket. Would this functionality suffice for your use-case?
All the Best, Torsten -- bash$ :(){ :|:&};: --------------------- http://www.unixer.de/ ----- Torsten Hoefler | Performance Modeling and Simulation Lead Blue Waters Directorate | University of Illinois (UIUC) 1205 W Clark Street | Urbana, IL, 61801 NCSA Building | +01 (217) 244-7736