When several fabric resource utilization percentages are high (on average > 75%), placement becomes more challenging if the netlist complexity is also high (high top-level connectivity, high Rent exponent, high average fanout). High clock frequency designs also come with additional placement challenges. In such situations, revisit the design features and consider removing non-essential modules until only one or two fabric resource utilization percentages are high. If logic reduction is not possible, review the other congestion alleviation techniques presented in this chapter.
Tip: Review resource utilization after
opt_design to get more accurate numbers, once unused logic has been
trimmed instead of after synthesis.