hierarchical power report: sub-design consumes more power than top design

[rabbitwayne]

Hi,

I have done a power estimation of my design in DC with power compiler and generated a power report in hierarchical way.
However, I feel strange that in the power report some of the sub-designs consume even more power than their top design.

For example, the Complex_ALU consumes even more total power than its top design fu5, and the RenameMapTable consumes
even more power than its top design Rename.

This makes no sense, right? I wonder why this happens? Thanks for your help!

Here are two snippets of my power report:

 

[OhaAmo]

Maybe each module power is calculated by itself, so a top module calculation is only the logic without lower hierarchies.

 

[rabbitwayne]

I don't think each module power is calculated by itself. I added the power of all the level-1 sub modules
and the total almost equals the power of the top module with minor difference. If I added up the power
of all the level-1, level-2 and level-3 sub modules, then the sum is much higher than the power of the
top module. So I don't think that the lower hierarchies are not counted in when calculating the power of
their top module.

 

[sruthikesh]

why to add "If I added up the power of all the level-1, level-2 and level-3 sub modules"?? because all sum of level-2 modules is the power of level-1 top module, adding all level-1 sub modules gives u the total power of the design. so, no need of adding level-2 and level-3 sub modules power to the total power.

 

[rabbitwayne]

why to add "If I added up the power of all the level-1, level-2 and level-3 sub modules"?? because all sum of level-2 modules is the power of level-1 top module, adding all level-1 sub modules gives u the total power of the design. so, no need of adding level-2 and level-3 sub modules power to the total power.

Yes, for the total power of the design I should only sum all level 1 modules. However, the problem with the power report is that some of the level 2 module consumes even more power than their level 1 top module. For example, the rename module. This does not make sense, right? The top module should include all power of its sub modules.