When bandwidth requirements are annotated in the QoS tab of the AXI-NoC IP reconfiguration wizard, that information is passed to the NoC compiler. The compiler attempts to solve for a set of bandwidth requirements. However, there is not always a solution. When a solution cannot be found, the compiler falls back to sub-optimal mode in which all bandwidths are relaxed to an achievable limit. In this case, the following critical warning is issued, which indicates that the solution does not reflect the requested bandwidths and will not meet the designer’s performance goals in hardware.
CRITICAL WARNING: [Ipconfig 75-4216] A NoC solution that meets the requested bandwidths could not be found. The following solution relaxes bandwidth requirements.This issue usually occurs when resources in the NoC are oversubscribed. For example, a design might be switching sites within the horizontal NoC (HNoC) when there is a high degree of fanout from masters in the vertical NoC (VNoC) columns. When this issue occurs, you must review the design or revise the bandwidths. Moving into hardware when this critical warning is present during implementation is counterproductive.