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    SubjectRe: [PATCH 1/9] exec: add a global execve counter
    On Sat, Mar 10, 2012 at 4:12 PM, Linus Torvalds
    <torvalds@linux-foundation.org> wrote:
    >
    > I wonder if we couldn't make something much cheaper, since we don't
    > actually care about it being globally incrementing, we just care about
    > it being globally unique.

    Actually, we don't even need it to be "globally unique" afaik. It
    really needs to be "relatively unique", since it's always compared
    within the confines of a particular task.

    So the problem with using the existing "self_exec_id" is that it's
    trivially the same across tasks. But a *tuple* of <struct
    task_struct, thread-specific exec_id> doesn't have that issue, so as
    far as I can tell we could easily make *that* the unique ID.

    I wonder if the number part of exec_id would even have to be 64-bit. I
    think I can do about 10000 execves per second if I make the program a
    small static one - and that's on a fast CPU. And it's a per-thread
    counter, so you can't scale it with lots of CPU's. So it would take
    something like four days to wrap. Hmm..

    Linus


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