Re: [chrony-dev] Let the kernel write the sys clock to RTC

["Piotr Grudzinski" <piotr@xxxxxxxxxxxxxxx>]

> > > > >  I would like to use chronyd on a small uClinux based system running 
> > > > > unattended 24/7.
> > > > >  The kernel can write the system time to the RTC every 11 minute if 
> > > > > the clock status ever
> > > > >  becomes SYNC; but it seems to be intentionally kept UNSYNC by 
> > > > > chronyd.
> > > > >  Reading some latest posts, there seems to be some agreement that 
> > > > > this would be a useful feature.
> > > > >  Are there any plans to have it implemented?
> > > >
> > > >  Please try the rtcsync directive added in the latest git push. Note
> > > >  that it can't be used when the normal RTC tracking is enabled.
> > > >
> > > >  -- 
> > > >  Miroslav Lichvar
> > > >
> > >
> > >  Thanks!
> > >  Still testing but seems to be working just fine.
> > >
> > >  --
> > >  Piotr
> >
> > Running on the same hardware, with this git version of chronyd program,
> > the frequency error in chrony.drift stabilizes at about -4ppm.
> > With ver 1.24, the error value is 27ppm. It doesn't seem to be right. (?)
>
> The drift rate depends both on the crystal frequency AND on the clock
> calibration done by Linus at bootup. Until the latest kernels the 
> calibration
> was all over the map, and the clock rate could change by 50PPM between two
> bootups. You do not tell us if there was a reboot between the two versions 
> of
> chrony. Nor do you tell us which kernel you are running (not even which
> operating system)
>
> It could of course also be a bug in chrony. Pls run the different versions 
> on
> the same system without rebooting it.

After reboot, before running chronyd, the adjtimex command shows the same
result.

/ # adjtimex
   mode:         0
-o  offset:       0
-f  frequency:    0
   maxerror:     16384000
   esterror:     16384000
   status:       64 (UNSYNC)
-p  timeconstant: 2
   precision:    1
   tolerance:    33554432
-t  tick:         10000
   time.tv_sec:  1274131047
   time.tv_usec: 836776
   return value: 5 (clock not synchronized)

And than the drift depends on which version of the chrony I will use. I 
always
start with the same chrony.drift file:

/ # cat /etc/chrony.drift
            27.5596               1.5206

--
Piotr


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