I've finished a rough implementation of MPI_T in MPICH2 and attached it to the MPI3Tools wiki page: https://svn.mpi-forum.org/trac/mpi-forum-web/attachment/wiki/MPI3Tools/mpit-... The implementation exposes all of MPICH2's current environment variable parameters via the "cvar" interface for both reading and writing. It also adds two performance variables for querying the lengths of the posted and unexpected receive queues. You should be able to play with it by applying the patch to r9009 of MPICH2's trunk and using the MPICH2 build instructions given here: http://wiki.mcs.anl.gov/mpich2/index.php/Getting_And_Building_MPICH2 The included patch is one large diff for convenient application ("patch -p1 < ..."). I can provide it as a patch set if anyone finds the current format too confusing to read (although there's still lots of boring boilerplate in that format). Included in the tarball are two simple test programs for checking that control variables and performance variables are generally usable. When using/inspecting the code, please keep in mind that this is not a polished, clean version of the code. Though it is certainly workable, I took a few shortcuts and left some parts incomplete in the interest of getting it out sooner rather than later. Some evolved version of this will likely end up in MPICH2's trunk (and next release) in the near future. IMO, what is currently here meets the implementation requirement for new MPI-3 features. -Dave