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?
01/29/2022, 12:09 PM
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.
01/31/2022, 5:38 AM
Would you give more details on what struggling means? Can you provide a test case?
01/31/2022, 11:28 AM
maybe try adjusting placement density:
set ::env(PL_TARGET_DENSITY) 0.45
02/02/2022, 11:12 AM
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.
02/02/2022, 12:32 PM
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