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    SubjectRE: why swap at all?


    There is not enough RAM address-space in even 64-bit machines
    to do a sort/merge of even a typical inventory with all the
    keys present in RAM. So you need multiple tasks, each with
    as much of the 64-bit address-space occupied by RAM, as
    possible. Even then, you need to do partial sorts, etc.

    It's not "bloat-ware" that requires getting as much free RAM
    as possible for an application, but the business of doing business.
    So, performance of data-intensive work such as the sort/merge
    is improved by writing the contents of sleeping tasks RAM to
    a storage device and using that RAM. It's just that simple.

    Many years ago, there was a small company that tried to sell
    a sort/merge engine (a dedicated CPU) to Digital because the
    problems with handling large databases was well known and
    interactive performance on VAX/11-750 machines sucked when
    database applications were being run (because their pages
    were being swapped). Of course the NIH syndrome took its
    toll and nobody ever got such an engine. The result being
    that everybody has performance problems when database
    operations are being run --even today, with different

    Any data-intensive application needs as much RAM as possible and
    that's never quite enough for best performance.

    Dick Johnson
    Penguin : Linux version 2.4.26 on an i686 machine (5570.56 BogoMips).
    Note 96.31% of all statistics are fiction.

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