Description
This rule checks the amount of stream stalls for AI Engine tiles.
Default Threshold
20.0
Explanation
Reducing stream stalls can improve AI Engine performance. Time AI Engine was in a stream stall. This could be due to multiple reasons such as streams being read faster than they are written to streams from the PL being clocked at a slower frequency, etc.
Recommendation
See Performance Analysis of AI Engine Graph Application during Simulation in AI Engine Tools and Flows User Guide (UG1076) for AIE_STREAM_STALLS.
You can resolve the stall by examining stream access patterns using trace results and increasing/balancing the FIFO depth on the stream, or maximizing the PL bandwidth to the AI Engine.
- Increase FIFO depth.
- Adjust stream read and write instructions in the loop.
- Multiple streams: Insert DMA FIFO or set different FIFO depth for different destination nets.
- PLIO: maximize AIE-PL interface bandwidth. For example: 64bit interface, highest frequency(1/2 AIE frequency) for PL, BLI register (channels with it).