GBA vs. PBA
Beginner
Two ways to check timing. One is fast and careful for every path. The other is slow and exact, for the paths that matter.
Novice
Two modes of timing analysis. Graph-based analysis is fast and checks everything, but it is cautious: at each point it assumes the worst case from any path passing through. Path-based analysis re-checks one path at a time with that path’s own conditions, which is more accurate but much slower.
Expert
Graph-based analysis stores one worst arrival and slew per pin; at a gate with several inputs, every path through the output inherits the worst input slew. Path-based analysis re-times a specific path with the slews that actually occur along it, so its slack is never worse. It costs several times the runtime, so flows run GBA everywhere and PBA on the paths that fail.