FIFO Depth Evaluation - FIFO Depth Evaluation - 2026.1 English

FIFO Depth Evaluation - FIFO Depth Evaluation - 2026.1 English - UG1702

Vitis Reference Guide (UG1702)

Document ID

UG1702

Release Date

2026-06-23

Version

2026.1 English

When the system deadlocks, the AI Engine compiler helps you evaluate the FIFO depth. You can add this depth to avoid deadlocks.

The tool computes these FIFO lengths from an AI Engine simulation for you. You can compile your graph with the AI Engine compiler using the --evaluate-fifo-depth flag.

After the tool compiles the code and runs the simulation, the Vitis Unified IDE displays the simulation run summary. The Nets table shows additional FIFO depth columns.

Figure 1. Nets Table With the FIFO Depth

Table 1. FIFO Depth Columns
Additional Column Name	Description
Estimated FIFO (Words)	FIFO depth that is recommended to be used in the graph to resolve the deadlock situation.
Peak FIFO (Words)	Maximum FIFO depth that is used to resolve the deadline situation. This is then used to compute the estimated FIFO.

You can use the estimated FIFO depth in the Estimated FIFO (Words) column to insert FIFOs with the specified length.

fifo_depth(net) = value;

In the code above, net is a connection to insert the FIFO.

Note: In AI Engine-ML, if the recommended FIFO depth is above the default threshold (40 words), use the option --swfifo-threshold to increase this limit.