Density overflow
Beginner
A measure of how much the parts are still piled on top of each other during the rough first pass.
Novice
During global placement, the share of cell area that sits in over-full bins (the small squares the chip is divided into for counting). It starts near 1, with every cell piled up, and the placer stops when it falls to a target such as 0.1.
Expert
Per bin, cell area minus capacity; summed over over-full bins and divided by total movable area. The convergence metric for Nesterov placers, and the trigger for timing-driven reweighting and routability inflation passes.
Explained in Placement (Design Flow).
See also: Global placement, Utilization (placement density).