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    SubjectRe: Is there a problem in timeval_to_jiffies?
    Hi,


    On Thu, 16 Sep 2004 02:54:39 -0700
    George Anzinger <george@mvista.com> wrote:

    > Timers are constrained by the standard to NEVER finish early.

    I just thought about that again and I think you are wrong.
    Maybe your statement is true for one-shot timers, but not for
    interval timers.

    No interval timer can guarantee, that the time between to
    triggers is always greater or equal to the time you programmed
    it.

    1 occurrence of a 1000ms timer,
    10 occurrences of a 100ms timer and
    100 occurrences of a 10ms timer should take the same time.

    For example:

    I want to have an interval timer for each second. Because of
    some special reason the time between two triggers became 1.2
    seconds.
    The question is now, when do you want to have the next timer?

    Your approach would trigger the timer in at least one second. But
    that is not the behaviour of an interval timer. An interval timer
    should trigger in 0.8 seconds because I wanted him to trigger
    _every_ second.
    If you want to have at least one second between your timers, you
    have to use one-shot timers and restart them after each
    occurrence.

    And in fact, I think that no userspace program can ever take
    advantage of your approach, because it can be interrupted
    everytime, so there is no guarantee at all, that there will be at
    least some fixed time between the very important commands. (for
    interval timers)


    So, what about adding this rounding value just to it_value to
    guarantee that the first occurrence is in it least this time?


    Best regards,

    Henry

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