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 core size. 

Last post Thu, Nov 13 2008 8:21 PM by gops. 3 replies.
Started by gops 12 Nov 2008 04:01 AM. Topic has 3 replies and 1437 views
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  • Wed, Nov 12 2008 4:01 AM

    • gops
    • Top 75 Contributor
    • Joined on Tue, Sep 23 2008
    • Trivandrum, Kerala
    • Posts 118
    • Points 2,505
    core size. Reply
    what is the criteria for selecting core utilization?? When i import a design into encounter , a core area comes by itself with a default core utilization.?On what basis the tool does this? How could i get an optimized value for my CORE AREA, CORE UTILIZATION?
    • Post Points: 20
  • Wed, Nov 12 2008 8:23 AM

    • Scrivner
    • Top 100 Contributor
    • Joined on Thu, Oct 9 2008
    • Ridgeland, MS
    • Posts 75
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    Re: core size. Reply

     You select core utilization based on your experience with how well your designs route using a particular technology.

    I think the default core utilization that FE uses is 70%. In my experience this value has worked pretty well across all the technologies that I've used. However, you may decide on a higher core utilization if, in your experience, your designs generally have plenty of free area and/or little routing congestion after post-route optimization.

    • Post Points: 20
  • Wed, Nov 12 2008 11:49 AM

    • Kari
    • Top 10 Contributor
    • Joined on Tue, Jul 15 2008
    • Cary, NC
    • Posts 693
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    Re: core size. Reply

     It really depends on the technology, library, number of routing layers, etc. It can also depend on the timing and how much timing margin you want. For example, if you want to fix hold timing with 100ps extra margin, you will need more room for buffers. I typically start a block at about 65%. Sometimes we find we need a lower util, sometimes we find we can squeeze it tighter. It can also depend on how much of your design is std cells and how much is RAM or other IP.

     - Kari

    • Post Points: 5
  • Thu, Nov 13 2008 8:21 PM

    • gops
    • Top 75 Contributor
    • Joined on Tue, Sep 23 2008
    • Trivandrum, Kerala
    • Posts 118
    • Points 2,505
    Re: core size. Reply
    Thanks Scrivner and Kari.

    I think i should fix my core size by multiple alterations by analysing my timing reports
    • Post Points: 5
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Started by gops at 12 Nov 2008 04:01 AM. Topic has 3 replies.