Hi, does anyone have any tips for how to debug a “Routing congestion too high” error during global routing? I’ve tried increasing the die size quite a bit (got my design down to 2% utilization), but still seeing this problem. I’ve tried tweaking various config numbers as well, like the global route padding and global routing layer adjustments. Is there a way to get more detailed output (e.g. where in the design the congestion is occurring)? Thanks!

Did you also adjust the PL_TARGET_DENSITY? This will spread out cells rather than just reserve global routing space through the adjustments.

I just ran some experiments adjusting the placement target density and while it doesn’t seem to be affecting cell placement, the router is still reporting things being too congested. I tried values of 0.6, 0.3, 0.1 and 0.01.

if your macros are too close together that can be an issue for congestion

you can also increase the halo around the macro for improved pin access