The Function Offload or Remote Procedure Call (RPC) Model is implemented using stubs as proxies.
A method stub , or simply stub , is a small piece of code used to stand in for some other code. The stub or proxy acts as a local surrogate for the remote procedure, hiding the details of server communication. The main code on the PPE contains a stub for each remote procedure on the SPEs. Each procedure on an SPE has a stub that takes care of running the procedure and communicating with the PPE.
When the program on the PPE calls a remote procedure, it actually calls that procedure's stub located on the PPE. The stub code initializes the SPE with the necessary data and code, packs the procedure's parameters, and sends a mailbox message to the SPE to start its stub procedure.
