AIE_LOCK_STALLS - 2022.2 English

Vitis Guidance Messaging (UG1315)

Document ID
UG1315
Release Date
2022-10-19
Version
2022.2 English

Description

This rule checks the amount of lock stalls for AI Engine tiles.

Default Threshold

20.0

Explanation

Reducing lock stalls can improve AI Engine performance. Time AI Engine was in a lock stall. This could be due to multiple reasons such as buffers being read faster than they are written to or from streams beween the PL being clocked at a slower frequency, etc.

Recommendation

See this link in AI Engine Tools and Flows User Guide (UG1076) for AIE_LOCK_STALLS.

You can resolve the stall by examining buffer access patterns using trace results and acquiring and releasing buffers on time. Use of local buffers may also resolve the issue. You should also ensure the PL interface throughput matches the AI Engine throughput in the case the PL interface is either the source or destination of the stalls.

  • Use PING-PONG buffer (default).
  • Balance throughput between kernels.
  • Acquire and release buffer in-time. Use local buffer as needed.