quicklogic: investigate negative cost warnings #1437
Description
During routing VPR prints a lot of negative cost warnings:
Warning 14404762: Cost is negative? cost = -2.352, bucket = -2147483648
It is unclear if this is caused by the timing data we use, bug in timing import or a bug in timing model.
Metadata
Metadata
Assignees
Labels
No labels
Type
Projects
Milestone
Relationships
Development
No branches or pull requests
Participants
Activity
tpagarani commentedon Apr 22, 2020
We see that route.log is taking up to 2GB space with these warning messages.
Could this also be causing increased run time in router?
litghost commentedon Apr 22, 2020
The cost function can never be negative in a sensical timing model. A negative cost is a signal that travels backwards in time.
litghost commentedon Apr 22, 2020
Also the units on the timing driven router is seconds, so a cost of -2.3 seconds is pretty crazy.
kgugala commentedon May 6, 2020
This has been fixed by bumping VPR version. Negative costs do not appear in the routing anymore.