title: How does MPI_Send work when the application buffer size is greater than MPI buffer size?
body: <p>How does <code>MPI_Send()</code> communicate the data to the receiving process if the size of the sending data is greater than the MPI buffer size? For example, let's say that I want to send 10 bytes of data (i.e., the size of my application buffer is 10B) in a single send message, but the MPI buffer has a fixed size of 6B. In this case, how does <code>MPI_Send()</code> send the data? Does it transfer first 6B and then transfer the remaining 4B? Or does it transfer only 6B?</p>