On Thu, Nov 10, 2011 at 21:14, Kai Germaschewski <[email protected]>wrote:

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.

What sort of configurations were these?

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.

I agree, this is mostly cosmetic, but there are more MPI-2 features that would also be useful. There are places where having MPI 1-sided would greatly simplify, for example.