[EMAIL PROTECTED] wrote:
> Hi Gilles,
>
> Thank you for your answer!
>
> -------- Original-Nachricht --------
> Datum: Fri, 20 Apr 2007 22:27:16 +0200
> Von: Gilles Chanteperdrix <[EMAIL PROTECTED]>
> An: [EMAIL PROTECTED]
> CC: [email protected]
> Betreff: Re: [Xenomai-help] Timer frequency
>
> > [EMAIL PROTECTED] wrote:
> > > Hi folks,
> > >
> > > does Xenomai adjust the system timer frequency? I probably does, so how
> > can I find out the frequency on my system?
> >
> > See:
> > http://www.xenomai.org/documentation/branches/v2.3.x/html/api/group__native__timer.html#g66f026b0ac68ef3acde0e6d1bdb6baaf
> >
> > In short, by default, the system timer is handled in aperiodic mode,
> > which means that there is no timer frequency: the system timer is
> > programmed at each software timer event to tick at next event.
>
> Does the Linux-Kernel need to be triggered every now and then to
> adjust system clock? I know that in times of DOS, the system timer
> had to occur every 18.3 seconds, and I have heard that Linux adjusted
> this for better scheduling. Do you know how often Xenomai issues a
> timer irq during idle phases?
On most architectures, one of the tasks of Xenomai nucleus is to handle
a periodic software timer which emulates the system timer used by
Linux. The frequency of this timer is the same as the one expected by
Linux, it depends on CONFIG_HZ.
There is at least on exception to this scheme: the x86 with local
APIC. In this case, Xenomai uses the local APIC as system timer, and
Linux continues to use the PIT.
--
Gilles Chanteperdrix.
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