Dataflow Optimization - 2021.2 English

Vitis Unified Software Platform Documentation: Application Acceleration Development (UG1393)

Document ID
UG1393
ft:locale
English (United States)
Release Date
2021-12-15
Version
2021.2 English

Dataflow optimization is a powerful technique to improve the kernel performance by enabling task-level pipelining and parallelism inside the kernel. It allows the v++ compiler to schedule multiple functions of the kernel to run concurrently to achieve higher throughput and lower latency. This is also known as task-level parallelism. To help, you need to understand the best practices for writing good software for execution on the FPGA as discussed in Optimizing for Throughput in the Vitis HLS User Guide (UG1399).

The following figure shows a conceptual view of dataflow pipelining. The default behavior is to execute and complete func_A, then func_B, and finally func_C. With the pragma HLS dataflow enabled, the compiler can schedule each function to execute as soon as data is available. In this example, the original top function has a latency and interval of eight clock cycles. With the dataflow optimization, the interval is reduced to only three clock cycles.

Figure 1. Dataflow Optimization