Hi everyone, I am fishing for expert tips if OpenLane is struggling in the detailed router phase. I think the design is not space constrained (utilization set to 20%). Any useful parameter settings that I could try, or things to watch for in the log files?

As a non-expert, I would suggest to relax the CLOCK_PERIOD, in case you haven't done that yet. It only works for me when I use 30ns, instead of a realistic one such as 5 ns for instance.

Would you give more details on what struggling means? Can you provide a test case?

maybe try adjusting placement density:

set ::env(PL_TARGET_DENSITY) 0.45

Thanks for all the tips so far. What I found is that if you go with absolute size, then giving a block way too much area causes issues with routing, interestingly. So reducing the available area (and setting density accordingly) actually helps.

Its likely that changing the area just changed the placement and happened to resolve some routing issue. If you can provide a test case for the problem you could open a GH issue