Design Analysis and Programming

AI Engines provide high compute density through large amount of VLIW and SIMD compute units by connecting with each other through innovative memory and AXI4-Stream networks. When targeting an application on AI Engine, it is important to evaluate the compute needs of the AI Engine and data throughput requirements. For example, how the AI Engine interacts with PL kernels and external DDR memory. After the compute and data throughput requirements can be met for AI Engine, the next step involves divide and conquer methods to map the algorithm into the AI Engine array. In the divide and conquer step, it is necessary to understand vector processor architecture, memory structure, AXI4-Stream, and cascade stream interfaces. This step is usually iterated multiple times. At the same time, each single AI Engine kernel is optimized and the graph is constructed and optimized iteratively. AI Engine tools are used to simulate and debug AI Engine kernels and the graph. The graph is then integrated with PL kernels, GMIO, and PS to perform system level verification and performance tuning.

In this chapter, the divide and conquer method to map the algorithm into data flow diagrams (DFD) is briefly introduced. Single kernel programming and multiple kernels programming examples are provided to illustrate how to do kernel partitioning by the compute and memory bound, single kernel vectorization and optimization, and streaming balancing between different kernels.