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What is the meaning of "Cell Utlilization"?

iamPSS

What is the meaning of Cell utilization and core utilization? PDF given in another forum with the same concept/question is bit confusing. What I understood is

Cell utilization = (Total number of cells that are present in the die) / ( Maximum number of cells that can be placed in the die) .


Core Utilization = (Total number of cells that are present in the core) / ( Maximum number of cells that can be placed in the core).

Is it right? Please correct me, if it isn't.

Thank you Slight smile

Parents

  • Hi,
    I assume your question is related to IC design, so I am moving the thread to the Digital Implementation forum.

    A standard cell library typically contains various cells with different area, so we do not consider the total number of cells,
    but the total area of the cells in the design.
    Hence the most basic calculation of the utilization is = (total area of all cells in the design) / (total peaceable area in the design).

    In the Innovus nomenclature, cell density considers the total area of all standard cells of the design, while core density also includes hard macros.
    Therefore
    cell density  = (total area of all std. cells in the design) / (total peaceable area in the design)
    core density = (total area of all std. cells and macros in the design) / (total peaceable area in the design)

    The concept was explained by Bob in this thread some years ago: core utilization and standard cell utilization

    In these calculations the peaceable area is the core area of the design; the core-to-die area where cells and macros cannot be placed is not included.
    On top of this comes also the consideration of how to treat (partial) placement blockages, place halos, pre-placed cells, physical only cells etc.

    There is an article that explains how different Innovus commands calculate the reported utilization:
    Understanding how density (utilization) is calculated by the different commands in Innovus

    Many users also have their own understanding/requirements of how utilization has to be calculated, so it is not uncommon to see custom reporting scripts to
    meet these requirements. There are some examples here: Examples of reporting cell information in a design

    Dimo

Reply

  • Hi,
    I assume your question is related to IC design, so I am moving the thread to the Digital Implementation forum.

    A standard cell library typically contains various cells with different area, so we do not consider the total number of cells,
    but the total area of the cells in the design.
    Hence the most basic calculation of the utilization is = (total area of all cells in the design) / (total peaceable area in the design).

    In the Innovus nomenclature, cell density considers the total area of all standard cells of the design, while core density also includes hard macros.
    Therefore
    cell density  = (total area of all std. cells in the design) / (total peaceable area in the design)
    core density = (total area of all std. cells and macros in the design) / (total peaceable area in the design)

    The concept was explained by Bob in this thread some years ago: core utilization and standard cell utilization

    In these calculations the peaceable area is the core area of the design; the core-to-die area where cells and macros cannot be placed is not included.
    On top of this comes also the consideration of how to treat (partial) placement blockages, place halos, pre-placed cells, physical only cells etc.

    There is an article that explains how different Innovus commands calculate the reported utilization:
    Understanding how density (utilization) is calculated by the different commands in Innovus

    Many users also have their own understanding/requirements of how utilization has to be calculated, so it is not uncommon to see custom reporting scripts to
    meet these requirements. There are some examples here: Examples of reporting cell information in a design

    Dimo

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