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Explorer
Posts: 227
Registered: ‎06-19-2014
Accepted Solution

What is "Number of Nodes with overlaps" parameter in implementation?

During routing of my design in vivado , i get a parameter in log report that is Number of Nodes with overlaps = some value

 

- Can someone tell what is this?

- What should be a nominal approx value of this parameter?

- If it has a high value like 20-30k, what will be impact on implementation? 


Accepted Solutions
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Explorer
Posts: 227
Registered: ‎06-19-2014

Re: What is "Number of Nodes with overlaps" parameter in implementation?

I found that the problem was in clock planniing. Implementation was taking veryyyyyyy long because i had used a regional buffer to clock my much tangled and large set of logic. Routing tool was taking too long because it was trying to route logic in one region. 

 I used BUFMRCE and then BUFR so that logic can take clock from adjacent regions also.  

Now implementation time is reduced to around 50 minutes, from 7 hours.

View solution in original post


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Administrator
Posts: 1,747
Registered: ‎06-14-2012

Re: What is "Number of Nodes with overlaps" parameter in implementation?

node overlaps means that you have multiple nets fighting for the same routing resource. If that number is high, this indicates some overall congestion problem, and there may be further clues in the Placer log.

 If you have the placed checkpoint, you can view the congestion map (estimated based on placement) from Window -> Metrics -> Vertical/Horizontal routing congestion. That may indicate which regions are giving problems and it may help develop a floorplan.

 

Hope this helps.

 

Regards

Sikta

Explorer
Posts: 227
Registered: ‎06-19-2014

Re: What is "Number of Nodes with overlaps" parameter in implementation?

During routing i get in log file

 

Phase 4.2 Global Iteration 1
Number of Nodes with overlaps = 20013
Number of Nodes with overlaps = 7137
Number of Nodes with overlaps = 4033
Number of Nodes with overlaps = 2505
Number of Nodes with overlaps = 1144

 

Phase 4.3 Global Iteration 2
Number of Nodes with overlaps = 8172
Number of Nodes with overlaps = 1588
Number of Nodes with overlaps = 349
Number of Nodes with overlaps = 105
Number of Nodes with overlaps = 33
Number of Nodes with overlaps = 16
Number of Nodes with overlaps = 10
Number of Nodes with overlaps = 1
Number of Nodes with overlaps = 1
Number of Nodes with overlaps = 0

 

As you can see that the router eventually solves problem with overlapping nodes but it takes it around 6 hours to do so. 

Does floorplanning help minimize initial figure of  "Number of Nodes with overlaps = 20013" ?

Administrator
Posts: 1,747
Registered: ‎06-14-2012

Re: What is "Number of Nodes with overlaps" parameter in implementation?

Please analyse the congestion metrics as listed in the earlier post and then floorplan the area where you see congestion numbers to be high.

 

Floorplanning definitely helps in reducing congestion.

 

Regards

Sikta

Explorer
Posts: 227
Registered: ‎06-19-2014

Re: What is "Number of Nodes with overlaps" parameter in implementation?

Hi Sikta,

         i am attaching the device view which is showing where is the congestion in horizontal routing (the pink area).

Now what's next? how to floorplan to remove this congestion? any document?

Untitled.png
Explorer
Posts: 227
Registered: ‎06-19-2014

Re: What is "Number of Nodes with overlaps" parameter in implementation?

my problem is not solved yet

Highlighted
Explorer
Posts: 227
Registered: ‎06-19-2014

Re: What is "Number of Nodes with overlaps" parameter in implementation?

I found that the problem was in clock planniing. Implementation was taking veryyyyyyy long because i had used a regional buffer to clock my much tangled and large set of logic. Routing tool was taking too long because it was trying to route logic in one region. 

 I used BUFMRCE and then BUFR so that logic can take clock from adjacent regions also.  

Now implementation time is reduced to around 50 minutes, from 7 hours.