Difference results when re-run placedesign

Hi DN .

As we know that several factors will involved which cause difference in  results.

BTW I dent get your changing topics on power grid ??

There are some default options which play a very imported role during placement and preplacement  optimization.

I think that you are have explicitly specified (noTimingDriven) option in setPlaceMode.

Are you expecting default RC factor setting , if YES then below is the method to set it.

##### Set RC Factor #####

setRCFactor -defcap 1.000 -detcap 1.000 -res 1.000

FYI . suggestions from manual :

Examples

_ The following commands perform non-timing-driven placement:

setPlaceMode -noTimingDriven

placeDesign

_ The following commands disable scan chain reordering:

setPlaceMode -noReorderScan

placeDesign

_ The following command disables the pre-placed buffer tree removal:

placeDesign -noPrePlaceOpt

_ The following command enables the in-place optimization flow:

placeDesign -inPlaceOpt

_ After the design is placed, the following command performs incremental placement, and

disables the pre-placed buffer tree removal:

placeDesign -incremental

Let me know if you need anything more.

Reg.
Mohan Ch

Thanks for your quickly reponses!

I know that several factor will involve that cause diffrence in result but I'm 
using the same options, same guides, same netlist,... from the previous run.
And it looks like the congestion is changing every time because some modules
are placed in an another areas.
The result has not much impact for the timing in generally. But for a high frequent design when a little bit change of congestions can harm the timing clean on some critical paths.
For more details what I've used:
- cadence_fe 04.20-s315_1_USR2
- Hierarchy netlist
- Timingdriven
- nopreplaceopt
- noreordescan

Regards,

Hi ,
I seems that you agreed that you have changed the placement of modules or fp. causing the same, As you know that trail route choose different paths when module placement change.
suggesion : try with "-incremental" option.
Yes I too agree that global congestion effects every design .
see the cause and avoid it by placing density screen .

Hi ,
I seems that you agreed that you have changed the placement of modules or fp. causing the same, As you know that trail route choose different paths when module placement change.
suggesion : try with "-incremental" option.
Yes I too agree that global congestion effects every design .
see the cause and avoid it by placing density screen .

Thanks , Non -AE

Hi I got you point what you mean in your mail,
I suggest you to add "Fence" option in your design instead of guide-OK
(The module is a hard constraint in the core design area.)
Note: Fence groups can potentially cause overlaps that cannot be corrected because
the Encounter software cannot move the cells out of the group.
So take care of each effective module target utilization (TU=%) value to represent their physical design .
Not an AE .