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    Sunday, March 29, 2009

    Reframe and Reuse: Extending The Capabilities Of EDA Tools Through Creative Reframing

    There's a joke that goes like this (from Mike Cook's List Of Math Jokes) :

    A physicist and a mathematician setting in a faculty lounge.
    Suddenly, the coffee machine catches on fire. The physicist grabs a
    bucket and leaps towards the sink, fills the bucket with water and
    puts out the fire. The second day, the same two sit in the same
    lounge. Again, the coffee machine catches on fire. This time, the
    mathematician stands up, gets a bucket, hands the bucket to the
    physicist, thus reducing the problem to a previously solved one.
    My interpretation: Make the physicist do all the work!

    There any many problems is ASIC design for which straightforward solutions/tools may not exist. You want the tool to consider timing, area, power and X. The rub is that the tool does not support measuring or optimizing for X. In such cases, it is worthwhile to explore the possibility of reframing X into something the tool does understand.

    By reframing the problem, you save yourself a whole lot of work:
    • You don't code, test and release a tool that supports concurrent optimization of X, timing, area, power,..
    • You don't create a tool that optimizes only X and spend time iterating between X optimization and standard optimization
    • You get to leverage the powerful algorithms built into your EDA tool to concurrently optimize for timing, area, power, X, Y, Z, ...
    For example, if X is uniform placement density and the tool does not explicitly support it, you can recast the problem as one of uniform/max/min metal density (which is supported via the DRC engine). Using virtual (user-created) metal layers and associated density rules to represent the placement density, enhance the cell's physical view such that the tool sees that the entire area of the cell is covered with one big piece of virtual metal. During optimization, the tool will try and meet the virtual layer density requirements (representative of uniform placement density) along with its standard cost functions (area, timing, power,etc).

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