Addressing Congestion - 2022.1 English

UltraFast Design Methodology Guide for Xilinx FPGAs and SoCs (UG949)

Document ID
UG949
Release Date
2022-06-08
Version
2022.1 English

Congestion can be caused by a variety of factors and is a complex problem that does not always have a straightforward solution. The report_design_analysis congestion report helps you identify the congested regions and the top modules that are contained within the congestion window. Various techniques exist to optimize the modules in the congested region. The report_qor_suggestions can automate the resolution of many of the items that cause congestion.

Tip: Before you try to address congestion with the techniques discussed in the following sections, make sure that you have clean constraints and you followed the clocking guidelines recommended by Xilinx. Excessive hold time failures (or negative hold slack) and clock uncertainties require the router to detour, which can lead to congestion. Avoid overlapping Pblocks, which can also cause congestion.