[ntp:questions] What level of timesynch error is typical onWinXP?

Miroslav Lichvar mlichvar at redhat.com
Mon Oct 25 16:46:33 UTC 2010


On Fri, Oct 22, 2010 at 11:39:47AM +0100, David J Taylor wrote:
> Thanks, Dave.  I may be missing something here, but it seems to me
> that 4.2.7p58 still takes a number of hours to reach the accuracy
> limits where thermal effects dominate.  It's that which matters to
> me, rather than something in the first few minutes.  I agree the
> graphs would not show such short time-scale initial disturbances.

Did the clock frequency change before you started the new version?

I played with the latest ntp-dev a bit and there indeed is a
improvement on start, mainly when the initial offset is around
0.01-0.05s. But the frequency error has to be very small to make a
difference, see these plots:

http://mlichvar.fedorapeople.org/tmp/ntp_start_offset.png
http://mlichvar.fedorapeople.org/tmp/ntp_start_freq.png

Also, I've noticed when ntpd is started without driftfile and the
initial offset is over 0.05 second, the overshoot can easily reach 100
percent, is this expected?

-- 
Miroslav Lichvar



More information about the questions mailing list