How to Understand the Congestion Report in Design Compiler Graphical

I have a congestion report that includes the following information

Both Dirs: Overflow = 48090 Max = 15 (1 GRCs) GRCs = 47264 (0.18%)
H routing: Overflow = 26229 Max = 12 (1 GRCs) GRCs = 26149  (0.10%)
V routing: Overflow = 21861 Max = 4 (3 GRCs) GRCs = 21115  (0.08%)

The “Max” value in “Both Dirs” reports the largest total violation in both horizontal and vertical directions per global route cell.

The “Max” value in “H routing” reports the largest total violation in the horizontal direction, and
the “Max” value in “V routing” reports the largest total violation in the vertical direction.

For example,

if the cell that has the largest violation in the horizontal direction has a Max value of 12, and
it has a Max value of 3 in the vertical direction, the Max number in "Both Dirs" is 15.

The "GRCs" value is the total number of global routing cells with any violation.

The percentage (%) value is the percentage of global routing cells that have violations out of the total number of global routing cells in the design.


In the report you provided, there are 26,149 global routing cells that have violations in the horizontal direction and 21,115 global routing cells that have violations in the vertical direction.

The report for both directions indicates that 47,264 global routing cells have violations in the horizontal direction or the vertical direction.