14.1. More on Point-to-Point Communication

In Chapter 13, you were introduced to point-to-point communication, the communication between a pair of cooperating processes. The two most basic commands used for point-to-point communication are MPI_Send and MPI_Recv. Several variations on these commands that can be helpful in some contexts are described in this section.

14.1.1. Non-Blocking Communication

One major difference among point-to-point commands is how they handle buffering and the potential for blocking. MPI_Send is said to be a blocking command since it will wait to return until the send buffer can be reclaimed. At a minimum, the message has to be copied into a system buffer before MPI_Send will return. Similarly, MPI_Recv blocks until the receive buffer actually contains the contents of the message.