Instead of having multiple directly accessible arguments, you get a pointer into main memory and the SPE has to issue DMA requests to get the pointed-to data from main memory.

Back to the API: the PPE can pass a single pointer into the program, so multiple arguments have to be bundled up. My solution is this.

A reference is an application specific pointer to an object that usually lives in a larger context, such as a server or cluster, and is used by multiple parties.