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quicklogic: investigate negative cost warnings #1437

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kgugala opened this issue Apr 22, 2020 · 4 comments
Closed

quicklogic: investigate negative cost warnings #1437

kgugala opened this issue Apr 22, 2020 · 4 comments
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@kgugala

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@kgugala
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kgugala commented Apr 22, 2020

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.
@kgugala kgugala self-assigned this Apr 22, 2020
@tpagarani
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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
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The cost function can never be negative in a sensical timing model. A negative cost is a signal that travels backwards in time.

@litghost
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litghost commented Apr 22, 2020 •
edited

Also the units on the timing driven router is seconds, so a cost of -2.3 seconds is pretty crazy.

@kgugala
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kgugala commented May 6, 2020

This has been fixed by bumping VPR version. Negative costs do not appear in the routing anymore.

@kgugala kgugala closed this as completed May 6, 2020
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@litghost @kgugala @tpagarani