13. SPU Communication, Part 2: Events, Signals, Mailboxes

Direct memory access (DMA) gets all the attention, but the Cell provides other ways to communicate between processors. These methods, which include signals and mailboxes, are generally used to send control data or small, important pieces of information such as memory addresses.

Events and interrupts play a central role in this discussion. In many cases, it’s not enough to transfer data into an SPU’s local store (LS); the SPU needs to be alerted that new data has arrived. This can be accomplished with interrupts, which immediately tell the processing unit that an event has occurred.

The Cell provides three main mechanisms for data transfer: DMA, signals, and mailboxes. These topics can ...

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