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Difference results when re-run placedesign

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I've got every time a difference result when I ran placedesign (related to congestion) after I've changed some power grid even though the same placementguides have been used.
My question is how can I specify the startpoint  (sheetfactor ??? ) so that the placedesign should start at the same point.

Thanks.


Originally posted in cdnusers.org by DN
Parents

  • Posted By mohanch007 on 3/22/2006 6:27 PM

    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 add few more comments on "placedesign" command :

    Based on your explanation not only RC extraction tunes placement but also timing analysis, trail routing and placement option settings.

    So you also need to set

    setPrerouteAsObs ( example for placement obstructions)

    setPlaceMode ( you can specify max touting layer )

    Trial Route Option (you need to specify same for every trail).

    Let me know how your trail route congestion report was every time you run.

    Reg.
    Mohan Ch




    Originally posted in cdnusers.org by mohanch007
Reply

  • Posted By mohanch007 on 3/22/2006 6:27 PM

    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 add few more comments on "placedesign" command :

    Based on your explanation not only RC extraction tunes placement but also timing analysis, trail routing and placement option settings.

    So you also need to set

    setPrerouteAsObs ( example for placement obstructions)

    setPlaceMode ( you can specify max touting layer )

    Trial Route Option (you need to specify same for every trail).

    Let me know how your trail route congestion report was every time you run.

    Reg.
    Mohan Ch




    Originally posted in cdnusers.org by mohanch007
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