Unexpected Messages

The Unexpected messages portion of the Message Queue Window shows information for retrieved and enqueued messages which are not yet matched with a receive operation.

Some MPI libraries such as MPICH 1.1.1 only retrieve already received messages as a side effect of calls to functions such as MPI_Recv() or MPI_Iprobe(). (In other words, while some versions of MPI may know about the message, the message may not yet be in a queue.) This means that TotalView cannot list a message until after the destination process makes a call that retrieves it.