| Sender mode | Notes | Synchronous?
|
| Synchronous send | Message goes directly to receiver.
Only completes when the receive has begun | synchronous |
| Buffered send | Message is copied in to a "buffer" (provided by the
application).
Always completes (unless an error occurs), irrespective of receiver. | asynchronous
|
| Standard send | Either synchronous or buffered (into a fixed size
buffer
provided by MPI system) | both/hybrid |
| Ready send | Assumes the receiver is ready.
Always completes (unless an error occurs), irrespective of whether
the receive was ready. | neither |
| Receive | Completes when a message has arrived | |
