[LinuxPPS] Allan deviation survey

[Miroslav Lichvar]

On Fri, Sep 10, 2010 at 06:39:31PM +0200, Udo van den Heuvel wrote:
> On 2010-09-10 15:36, Udo van den Heuvel wrote:
> > Doesn't ntpd log this when configured?
> 
> In the loopstats?
> See http://fixunix.com/ntp/67783-format-loop-stats.html.
> 
> I might be mistaken if this is something else.

That's probably not accurate enough. To not negatively affect the
result, I think you would need to know when exactly was the frequency
changed and at what rate at which point was the offset applied. This
depends on kernel constants like SHIFT_PLL which are not visible in
userspace. Also kernel doesn't seem to apply the changes immediately
after adjtimex() call, but according to an internal timer.

-- 
Miroslav Lichvar