On Thu, Nov 10, 2011 at 8:43 PM, Jed Brown <[email protected]> wrote: How do we find out who needs pre-MPI-2.0? Just a (kinda arbitrary) data point: I introduced MPI_IN_PLACE in my code a year or so ago (not realizing that it requires MPI-2.0 at the time) and within a year, I hit two cases of machines that were still running MPI 1.x -- and the code doesn't get to run in all that many places in the first place. Having said that, I think it's generally a good idea to not keep backwards compatibility cruft around forever. OTOH, requiring MPI2 just for MPI_IN_PLACE isn't a real convincing case, since it's so easy to do the same with MPI1. --Kai -- Kai Germaschewski Assistant Professor, Dept of Physics / Space Science Center University of New Hampshire, Durham, NH 03824 office: Morse Hall 245E phone: +1-603-862-2912 fax: +1-603-862-2771