Meeting 2015 01

January 2015 OMPI Developer's Meeting

This is a standalone meeting; it is not being held in conjunction with an MPI Forum meeting.

Logistics

Doodle for choosing the date: https://doodle.com/zzaupgxge9y6medu

• Date: 9am Tuesday, January 27 through 3pm Thursday, January 29, 2015
• Location: Cisco Richardson facility (outside Dallas), building 4:

Cisco Building 4
2200 East President George Bush Highway
Richardson, Texas 75082-3550

Google maps link: https://goo.gl/maps/SNrbu

Attendees

Local attendees:

• (*) Jeff Squyres - Cisco
• (*) Howard Pritchard - Los Alamos
• (*) Ralph Castain - Intel
• (*) George Bosilca - U. Tennessee, Knoxville
• (*) Dave Goodell - Cisco
• (*) Edgar Gabriel - U. Houston
• (*) Vish Venkatesan (not Tuesday) - Intel
• (*) Geoff Paulsen - IBM
• (*) Joshua Ladd - Mellanox Technologies
• (*) Rayaz Jagani - IBM
• (*) Dave Solt - IBM
• (*) Perry Schmidt - IBM
• (*) Naoyuki Shida - Fujitsu
• (*) Shinji Sumimoto - Fujitsu
• (*) Stan Graves - IBM
• (*) Mark Allen - IBM
• ...please add your name if you plan to attend...

(*) = Registered (by Jeff)

Remote attendees

• Nathan Hjelm - Los Alamos
• Ryan Grant - Sandia (planning to attend for the MTL and 1.9 branch discussions)

Topics

• Jeff/Howard: Branch for v1.9
• Jeff/Howard: Jenkins integration with Github:
  • how do we do multiple Jenkins servers? (e.g., running at different organizations)
• Ralph: Review: v1.8 series / RM experience with Github and Jenkins and the release process
  • Ralph's feedback: lots more PRs than we used to have CMRs
  • Ralph's feedback: people seem to be relying on Jenkins for correctness, when Jenkins is really just a smoke test
• Nathan: Performance of freelists and other common OPAL classes with OPAL_ENABLE_MULTI_THREADS==1 (as discussed in [GitHub]). Part of this is done already -- LIFO is a bit faster now (with threads), etc.
• Ralph: Scalable startup, including:
  • Async modex, static endpoint support
  • Re-define the role of PML/BTL add_procs: need to move to a more lazy-based setup of peers
  • Memory footprint reduction
• Ralph: RTE-MPI sharing of BTLs
• Ralph: Data passing down to OPAL
  • Revising process naming scheme
  • MPI_Info
• Howard: Progress on async progress
  • What happened to this proposal: http://www.open-mpi.org/community/lists/devel/2014/02/14170.php
• Jeff: Progress on thread-multiple support
• Ralph/Nathan: MTL overhead reduction
• Intel/LANL: MTL selection issue (PSM vs. OFI)
• Nathan: Enhance MTL interface to include one-sided and atomics
• Ralph: Error response planning (e.g., BTL error propagation up from OPAL into ORTE and OMPI, particularly in the presence of async progress).
• Ralph: Collective switching points & MPI tuning params - what is required to change them. Had a discussion brought up by Mellanox, and we never finished this.
• Vish: Memkind integration: see http://www.open-mpi.org/community/lists/devel/2014/11/16320.php
• Jeff: MPI extensions: MPIX_ prefix, or OMPI_ prefix?
• Ralph: PMIx and ORCM updates
• Nathan: --disable-smp-locks: remove this option?
  • See RFC email http://www.open-mpi.org/community/lists/devel/2015/01/16736.php
  • See, in particular, George's replies
• Fujitsu: future plans for Open MPI development
• extracting libnbc core from the collective component into a standalone directory such that it can be used from OMPIO and other locations
• Jeff: libtool 2.4.4 bug / libltdl may no longer be embeddable. Should we embed manually, or should we just tell people to have libltdl-devel installed?
• Howard/George: fate of coll ML
• see http://www.open-mpi.org/community/lists/devel/2015/01/16820.php
• who owns it?
• should we try to fix it or disable by default?

Since this will be a full meeting in itself, we'll have a good amount of time for discussion, design, and for hacking!

Resolved

• Jeff: libtool 2.4.4 bug / libltdl may no longer be embeddable. Should we embed manually, or should we just tell people to have libltdl-devel installed?

  • Resolved: let's stop embedding; we'll always link against external libltdl.
  • However: this means people need to have the libltdl headers installed (e.g., libltdl-devel RPM). We don't care about telling developers to do this, but we are a little worried about telling users to do this (because it raises the bar for building Open MPI -- the assumption that libltldl-devel is almost certainly not installed on most user machines).
  • The question becomes: what is configure's default behavior when it can't find ltdl.h?
    1. Abort
    2. Just fall back to --disable-dlopen behavior (i.e., slurp in plugins)
  • Let's bring up the "default behavior" issue as an RFC / beer discussion.

• Branch for v1.9

  • We need to make a feature list for v1.9.0 and decide when it makes sense to branch