Re: High Performance Counter.

Discussion in 'C Programming' started by Eternal Vigilance, Jul 9, 2003.

  1. I think it just resets when the CPU is powered up, but never thought of looking
    into it
    since always have used it as a relative time difference (endtime-starttime).

    It would probably be hard to synchronize to an external (high accuracy) clock as
    its count is so fast
    that the non-deterministic (timewise) operation of any program would be off by
    some significant count
    by the time any set instruction could be run.


    Skybuck Flying wrote:

    > Hi,
    >
    > I have some questions about the high performance counter.
    >
    > 1. When the power is off does the high performance counter continue to tick
    > ?
    >
    > 2. If not then how is the high performance counter initialized at boottime ?
    >
    > 3. Where can I find more information about the chip(s) for the high
    > performance counter ?
    >
    > 4. Is it possible to reset the high performance counter via a software call
    > ?
    >
    > 5. How is the frequency related to the hardware ? I know it's different per
    > processor... but is it for example different depending on memory speed ? or
    > does it always have a fixed frequency ?
    >
    > ( note: I changed the windows xp system time to see what would happen, it
    > did not affect the high performance counter, so it seems not related to each
    > other )
    >
    > p.s.: I know it's off-topic in some newsgroups I posted too but euhm... I
    > didn't know what newsgroup was best suited for it, I hope you understand :)
    >
    > Thank you,
    > Skybuck.
    Eternal Vigilance, Jul 9, 2003
    #1
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  2. "Eternal Vigilance" <> wrote in message
    news:...
    > I think it just resets when the CPU is powered up, but never thought of

    looking
    > into it
    > since always have used it as a relative time difference

    (endtime-starttime).

    Yeah... I did a little test and it seems it randomly sets it.

    I also use it as relative time... I wondered if it could be used for
    something else as well.

    So that idea is not 'out the window' :)
    Skybuck Flying, Jul 9, 2003
    #2
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