2015-10-31 17:33 GMT+01:00 William Gropp <[email protected]>:

Under the interpretation of using whether the target process has observed, rather than received the message, a consistent interpretation is that the MPI_Cancel fails at the source, as it would if the message had been received.

But does that satisfy the requirement that "[i]f a communication is marked for cancellation, then a MPI_WAIT call for that communication is guaranteed to return, irrespective of the activities of other processes (i.e., MPI_WAIT behaves as a local function); similarly if MPI_TEST is repeatedly called in a busy wait loop for a cancelled communication, then MPI_TEST will eventually be successful"? As far as I can see, MPI_Wait for the matched send cannot be local, since it can complete only once the receiver actually receives the message. I understand that cancelling of sends is in the process of being phased out of the standard, but I would like to find out how/if it's possible to implement this feature correctly given that it is, currently, a part of the standard. Marek Tomáštík