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Scholar embedded
Scholar
1,094 Views
Registered: ‎06-09-2011

PlanAhead incorrect resource usage

Hi all,

I have a design with a pblock that is reported by Plan Ahead that uses number of resources. As I look at the defined area in Plan Ahead I see that defined pblock is enough for PAR to place it there. However, I receive error messages during PAR and it fails placing my block in that defined area?!. I am wondering where I can find exact information regarding resource usage of a block in ISE14.7.

Below picture shows statistics of resource usage of that block in Plan Ahead:

 

Placement Resources.jpg

I expect the PAR to be able to route the design completely as the area has enough information. Below is error:

 

Running delay-based LUT packing...

 

ERROR:Pack:242 - The area group pblock_FrameParser_INST has 179 slice
components. The maximum size for the area group is 168 physical sites.
Running related packing...
Updating timing models...

 

I would appreciate any help,

Hossein

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3 Replies
Moderator
Moderator
1,044 Views
Registered: ‎11-04-2010

Re: PlanAhead incorrect resource usage

Hi, @embedded ,
What device are you using?

What's result of the below command in PA?

report_utilization -cells [get_cells FrameParser_INST]

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Scholar embedded
Scholar
1,021 Views
Registered: ‎06-09-2011

Re: PlanAhead incorrect resource usage

Hi @hongh,

I am working on XC3S400 device. I used that command. However, it prints no information regarding resource usage. I see below message:

"This LUT count does not take into account thta LUTs may be merged later in the flow to take advantage of the O5 & O6 outputs. Please see Post Placement utilization report to get final LUT count after LUT combining has occured." And, you know that report contains final resource utilization in whole design not in a specific module.

 

I am wondering why PlanAhead is giving wrong information in statistics of a module!. Maybe its a bug!.

 

 

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Moderator
Moderator
1,006 Views
Registered: ‎11-04-2010

Re: PlanAhead incorrect resource usage

Hi, @embedded ,

It seems report_utilization command doesn't work well in PA. It only works in Vivado.

 

Then you can try to enlarge the Pblock area and complete the MAP. With -detailed option in mapping, you can see the actual utilization for the target module in XX.mrp.

If the SLICE number of INST is much smaller than PA estimation, it might be PA's bug. 

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