On Apr 24, 2009, at 8:38 AM, Jeff Hammond wrote:

Active messages are very appealing to me but I'm not aware of a library implementation (F77 and C compatible) that runs on BlueGene/P, Cray XT, Infiniband and Myrinet. Can you point me to one?

MX does support a limited active message model. The application can register an unexpected handler that is called whenever MX receives a message for which the application has not pre-posted a receive. The handler has access to the match tag, the sender info, the length of the message, and the actual data if the length is 1 KB or less (small but useable). It is useful in filesystems where there are a lot of unexpected messages. It avoids having to pre-post a lot of generic receives. I believe Open-MX supports it as well. Scott