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    Subjectdifferences between MADV_FREE and MADV_DONTNEED
    Now that MADV_REMOVE is in, should we discuss MADV_FREE?

    MADV_FREE in Solaris is destructive and only works on anonymous memory,
    while MADV_DONTNEED seems to never be destructive (which I assume it
    means it's a noop on anonymous memory).

    Our MADV_DONTNEED is destructive on anonymous memory, while it's
    non-destructive on file mappings.

    Perhaps we could move the destructive anonymous part of MADV_DONTNEED to
    MADV_FREE?

    Or we could as well go relaxed and define MADV_FREE and MADV_DONTNEED
    the same way (that still leaves the question if we risk to break apps
    ported from solaris where MADV_DONTNEED is apparently always not
    destructive).

    I only read the docs, I don't know in practice what MADV_DONTNEED does
    on solaris (does it return -EINVAL if run on anonymous memory or not?).

    http://docs.sun.com/app/docs/doc/816-5168/6mbb3hrgk?a=view

    BTW, I don't know how other specifications define MADV_FREE, but besides
    MADV_REMOVE I've also got the request to provide MADV_FREE in linux,
    this is why I'm asking. (right now I'm telling them to use #ifdef
    __linux__ #define MADV_FREE MADV_DONTNEED but that's quite an hack since
    it could break if we make MADV_DONTNEED non-destructive in the future)

    Thanks.
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