vtr-verilog-to-routing icon indicating copy to clipboard operation
vtr-verilog-to-routing copied to clipboard

Published 20 hours ago • verified publisher icon verilog-to-routing

Set the maximum pres_fac

Open amin1377 opened this issue 11 months ago • 1 comments

This pull request introduces a new command line argument to set the maximum pres_fac, which is now defaulted to 1000.

The pres_fac coefficient is used to adjust the cost of an overused net by multiplying it with the number of nets overusing it. This adjustment encourages the router to explore alternative routes. Previously, the maximum value for this coefficient was set to an extremely large number, resulting in strange router behavior such as excessive ripping up connections toward the end of routing. To address this issue, the default maximum value is now set to 1000, providing more predictable router behavior. Additionally, users have the flexibility to adjust this value as needed via the command line.

amin1377 avatar Apr 02 '24 15:04 amin1377

QoR data? The one CI failure is a small circuit (alu4) that has a higher critical path delay. Not a real concern so OK.

vaughnbetz avatar Apr 04 '24 16:04 vaughnbetz

@amin1377 : please merge once CI passes.

vaughnbetz avatar May 23 '24 14:05 vaughnbetz

Thanks Amin. The code all looks good. Just for safety, can you run a VTR minimum channel width regtest to confirm QoR (min chan width, routing time, etc.) look OK for it?

vaughnbetz avatar May 29 '24 13:05 vaughnbetz

image

amin1377 avatar May 29 '24 21:05 amin1377

Looks good, thanks. I'll merge as soon as CI is green.

vaughnbetz avatar May 29 '24 21:05 vaughnbetz