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DC Topographical error: fail in placement: Over Utilization

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gaom9

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Hi, everyone.
I want to input the floorplan information of Encounter to DC(topographical_mode) to improve the timing of the design. The floorplan information is DEF file format, and it can be read into dc -topo by extract_physical_constraints command correctly, and the "compile_ultra -scan -num_cpus 2 -timing_high_effort_script -congestion" was executed correctly. But when the optimization finished, the tool shown the following error and exit. Can anyone help me about it? Thank you

Error: Fail in placement: Over Utilization
Severe Error: Fatal error: Placer did not complete. (PSYN-375)
Error: DC Topographical Failed to place the design. (OPT-1405)
Error: compile_ultra Topographical stage has abnormally terminated. (OPT-100)

Best regards!
 

Re: DC -topo Error

I believe this means that the utilization is more than 100%, so the die area is too small.

Run DC without the physical constraints and check what the netlist area is. If the area is bigger than your die area constraint, the you have to revisit your floorplan.

Also try without the congestion switch, since it might increase the area a bit.
 

Re: DC -topo Error

johanlo said:
I believe this means that the utilization is more than 100%, so the die area is too small.

Run DC without the physical constraints and check what the netlist area is. If the area is bigger than your die area constraint, the you have to revisit your floorplan.

Also try without the congestion switch, since it might increase the area a bit.

Thank johanlo.
I have found the reason. There are something wrong in the DEF file from Encounter, I changed a DEF file from ICC, the DC -topo worked well.
 

Re: DC -topo Error

Thank johanlo.
I have found the reason. There are something wrong in the DEF file from Encounter, I changed a DEF file from ICC, the DC -topo worked well.

I have a same issue right now. But this flow works well before.
Now I'm just wondering if it's caused by the version of ICC. I'm not sure.
But it's not the size of die area.
 

I had a similiar issue... the problem is when you specify the blockage over the memories or black boxes and that gets imported in the DEF. After that with the -timing_high and -congestion switches in the compile_ultra when the tool tried to improve the timing by adding buffers etc... even a small increase in the number of cells causes it to show the Error.
Gaom, it would be helpful to all if you could point out what difference did you spot between the two DEFs
 
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    pdude

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Hi, Gaom, could you please point out what difference did you spot between the two DEFs?
 

I had a similiar issue... the problem is when you specify the blockage over the memories or black boxes and that gets imported in the DEF. After that with the -timing_high and -congestion switches in the compile_ultra when the tool tried to improve the timing by adding buffers etc... even a small increase in the number of cells causes it to show the Error.
Gaom, it would be helpful to all if you could point out what difference did you spot between the two DEFs

HI, we have solved this issue recently.
Maybe you can refer to the following way:
the problem is caused by mismatch between DEF and RTL. To be more specific, there are wrong hierarchy paths of macro in DEF. However, the tool will still floorplan it but the real one declared in RTL will also be placed.

Guess what? there are two same macros during the DCT optimization flow. Therefore, it is the reason why the utilization is much bigger than expected.

If your problem is caused by another issue, please share with us. Thanks.
 

HI, we have solved this issue recently.
Maybe you can refer to the following way:
the problem is caused by mismatch between DEF and RTL. To be more specific, there are wrong hierarchy paths of macro in DEF. However, the tool will still floorplan it but the real one declared in RTL will also be placed.

Guess what? there are two same macros during the DCT optimization flow. Therefore, it is the reason why the utilization is much bigger than expected.

If your problem is caused by another issue, please share with us. Thanks.

That makes sense. Thanks !
 

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