High Performance Counter.

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3 total messages Started by Skybuck Flying Tue, 08 Jul 2003 14:54

#2248

Author: Skybuck Flying
Date: Tue, 08 Jul 2003 14:54

28 lines
2681 bytes

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.

Re: High Performance Counter.

#2244

Author: Eternal Vigilance
Date: Tue, 08 Jul 2003 23:28

41 lines
3237 bytes

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.

Re: High Performance Counter.

#2246

Author: Skybuck Flying
Date: Wed, 09 Jul 2003 01:16

15 lines
2260 bytes

"Eternal Vigilance" <wotan@oneeye.com> wrote in message
news:3F0B53D4.7A454BA2@oneeye.com...
> 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' :)

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