Complexity Field - 2024.2 English - 2024.1 English

Vivado Design Suite User Guide: Design Analysis and Closure Techniques (UG906)

Document ID
UG906
Release Date
2024-11-13
Version
2024.2 English

The complexity field allows you to report the complexity of the design netlist, which is a measure of the connectivity density throughout the hierarchy. This can be an early indicator of routing congestion. This section of the command is compile time sensitive, particularly on large designs. See Complexity Report.

Equivalent Tcl option: -complexity

When the Hierarchical Depth option is selected, you can select the levels of hierarchy underneath the top cell to calculate the rent coefficient. The top level is default, or it can be adjusted to lower levels by specifying by the -cells option in the Advanced tab. Using the cells option will reduce the number of hierarchies analyzed and speed up the calculation.

Equivalent Tcl option: -hierarchical_depth <arg>

The Rent Greater Than option limits the information displayed in the report to modules with a rent above the specified level and their children. Typically modules with values below this do not exhibit congestion. The default value is 0.6.

Equivalent Tcl option: -rent_greater_than <arg>

The Instances Greater Than option limits the number of hierarchical cells on which the Rent calculation is performed on. Typically small modules even with high Rent coefficients, will not exhibit congestion. Increasing this value typically lowers compile time of the command. The default value is 15000.

Equivalent Tcl option: -instances_greater_than <arg>

The Instances Lesser Than option limits the number of hierarchical cells on which the Rent calculation is performed on. Typically the resulting actions to reduce congestion will increase area and hence are best performed on hierarchical cells that are not any larger than need be. Reducing this value typically lowers compile time of the command. The default value is 100000.

Equivalent Tcl option: -instances_lesser_than <arg>

The Average Fanout Greater Than option limits the number of hierarchical cells on which the Rent calculation is performed on by calculating the average fanout of signals within the module and not performing the Rent calculation if it is below the threshold. High Rent coefficients combined with high average fanouts typically are the best estimated modules for predicting congestion. Increasing this value typically lowers compile time of the command. The default value is 3.0.

Equivalent Tcl option: -av_fanout_greater_than <arg>