[ntp:questions] Re: ntpd PLL and clock overshoot

user at domain.invalid user at domain.invalid
Wed Oct 18 15:39:45 UTC 2006


I upgraded to Netscape 7.2 on the hope that would fix the bogus from 
address. Stay tuned.

Using Linux of any version anywhere here is strictly forbidden. Does 
that answer your question?


Uwe Klein wrote:
> user at domain.invalid wrote:
>> Guys,
>> In all kernels I have seen over the last several years the adjtime() 
>> system call is implemented in the kernel/kern_clock.c kernel module. 
>> There may be a library wrapper for it, but the actual adjustment is 
>> done in the kernel at each timer interrupt.
> Hey user ;-)
> Which Linux SemiMajor version (are you | is being) referencing : 
> 2.[0,2,4,6] ?
> PRE:
>     i don't know shit about ntpd related timehandling with linux (yet).
>      I've done realtime stuff on linux 2.2, 2.4 ( started with 2.6 ).
>     up to now i have used one ntpd synced (black)box to do bookkeeping on
>     timeslip of my embedded and rather undermuscled (SC400/8MB) RT 
> thingies.
>     fixing slip by adjusting my timeconstants, doing nothing against 
> jitter.   
>     ( time corrections do not reach the RT clock anyway.)
> Which Linux SemiMajor version are you referencing 2.[0,2,4,6] ?   
> recent sources of linux 2.6.1n seem to be extensively revamped. the 
> mentioned
> files and functions are not present.
> "something" seems to have been moved into the high resolution timer stuff.
> How current is the ntpd developers picture of recent linux ?
>     I am in the process of building and deploying distributed sweep 
> receivers
>     (that replace a single 4 Band receiver at the end of several hundred 
> feet of koax)
>     that have to run in sync ( <10ms ).
>     my interest here is do i stay with my current method or can i leverage
>     ntpd to do housekeeping for my little boxes and adjust hardware 
> clockrate
>     in some way ( VCXO, or just heating up the builtin Xtal )
> uwe

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