On Fri, Jul 18, 2008 at 02:57:19PM -0400, Richard Treumann wrote:

The semantic provided by using MPI_REQUEST_FREE on an active send request is clearly useful and is clearly mandated by MPI 1.1.

My apologies, I wasn't reading the right part of the standard. It is clear and it is mandated, and it does restrict implementations in a way that seems odd. The sending side might have some cleanup work before it thinks the send is complete, yet the recieving side might conclude that the message is complete before the sender does. That's the 'spooky action at a distance' problem I was referring to. Now, the reason I was confused? When you google MPI_REQUEST_FREE, it lands you on the MPICH-1 manpage entry for MPI_REQUEST_FREE, which lacks most of the details of section 3.7.3 on the standard. At the least the manpages ought to refer to/link to the standard, or else they could be replaced by (for example) the OpenMPI manpages, which are much more complete. This doesn't excuse my carelessness, of course, but I'm probably not the only idiot googling routine names expecting complete info. -- greg