Slam Capacity


The slam system was designed to handle even very large designs. The limits of the database are below.

  • Maximum number of objects per cell: > 1,000,000,000
  • Maximum number of layers: 16300
  • Maximum number of datatypes: 256
  • Maximum hierarchical depth: 100
  • Maximum number of points in a polygon/path: 2040
  • Maximum string length of most names: 2048
  • Maximum cell name length: 1024 (Although stream limits this to 32)
  • Maximum view name length: 100
  • Largest stream file converted (as far as we know) 13GB
  • Estimated largest P&R block size: 100M cell placements (including fillers) requiring about 90GB of memory.
  • Chip size limited to memory size. As an example, a single chip could be composed of 4 unique 100M gate P&R blocks placed at the chip level requiring some 270GB of memory.

    Platform Capacity

    The following can be used as a general guide to virtual memory requirements for slam with P&R type databases. All component counts exclude filler cell placements, which can double or even triple placement counts.

  • Less than 750K placements; Less than 2GB and will operate under 32 bit Linux.
  • Greater than 750K placements; x86/64/linux required.

    If your design does not contain connectivity information, a substantially larger design will fit in the same memory footprint. Estimated platform limits are

  • Less than 1.5M placements; Less than 2GB and will operate under 32 bit Linux.
  • Greater than 1.5M placements; x86/64/linux required.

    The above are only estimates as every design will be slightly different. Some designs have more or less wiring per cell. Placement counts are used as a guide because it is a more commonly available parameter. Note the placement counts are all unique placements. For example 15 placements of a cell containing 50 placements counts as 65, not 750 placements.

    Please note that for reasonable performance, you should have physical memory of at least the size of the largest block. In the above 3M placement case, 4GB of physical memory is recommended as a minimum.

    Slam Performance

    Example on a 2GHz quad 16GB opteron
    12GB stream file
    5 minute conversion from stream to slam format
    1 minute to open database with all hierarchical levels displayed
    all times assume data has not been cached, and includes disk read time.