Explicit Packet Switching - 2022.2 English

AI Engine Kernel and Graph Programming Guide (UG1079)

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2022.2 English

Just as multiple AI Engine kernels can share a single processor and execute in a interleaved manner, multiple stream connections can be shared on a single physical channel. This mechanism is known as Packet Switching. The AI Engine architecture and compiler work together to provide a programming model where up to four stream connections can share the same physical channel.

The Explicit Packet Switching feature allows fine-grain control over how packets are generated, distributed, and consumed in a graph computation. Explicit Packet Switching is typically recommended in cases where many low bandwidth streams from common PL source can be distributed to different AI Engine destinations. Similarly many low bandwidth streams from different AI Engine sources to a common PL destination can also take advantage of this feature. Because a single physical channel is shared between multiple streams, you minimize the number of AI Engine - PL interface streams used. This section describes graph constructs to create packet-switched streams explicitly in the graph.