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    SubjectRe: New Feature Idea: Compress swap file
    On Thu, 19 Feb 1998, ;The Doctor What wrote:

    > Can't optimize this by compressing on a per page basis? I'm not overly

    It could, but you can never be sure exactly how big
    the page will be. It might even end up bigger than
    the uncompressed one, but you can't just allocate
    3k/page, because you'll get stuck on several pages
    that way.

    > familiar with the theory, but it seems that there is less to compress
    > (yeah, the compression isn't as good) and less for the CPU to worry about.

    In 2^12 bits (one page) you have 2^12 possible
    patterns. You can't guarantee to compress each
    of those, since there are only 2^12 - 1 patterns
    with less bits.

    Therefore, some pages can't be properly compressed
    and you'll need all kinds of fancy bookkeeping that
    may just compensate for the possible benefit...

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