[ntp:questions] NTPD can take 10 hours to achieve stability
snews at lordynet.org
Tue Apr 19 23:01:58 UTC 2011
> On 2011-04-19, David Lord <snews at lordynet.org> wrote:
>> David J Taylor wrote:
>>> "unruh" <unruh at wormhole.physics.ubc.ca> wrote in message
>>> news:slrniqpa40.ppu.unruh at wormhole.physics.ubc.ca...
>>>> Well, I think someone other than the current maintainers will have to
>>>> port it to windows. Since windows timekeeping is not the worlds best
>>>> anyway, it is probably true that the extra accuracy of chrony is
>>>> unnecessary. It does have a command line option "like ntpq -p"
>>>> provided by chronyc (depending on what you mean by "like").
>>>> What MRTG is I do not know.
>>>> If you are happy with ntpd, by allmeans stay with it.
>>> A pity that chrony will not be offered for Windows, at least for tests
>>> to see whether it lives up to its claims. There are times when a more
>>> rapid convergence would be welcome, such as the reboot of PC Molde
>>> around 13:30 yesterday:
>>> MRTG is a standard logging tool for network I/O which uses SNMP to
>>> produce the graphs I have quoted here many times for network throughput
>>> and timekeeping:
>>> I've written how to extend MRTG to monitor NTP timekeeping, and various
>>> other parameters such as disk space and temperature here:
>>> From chronyc I would need to be able to use a simple Perl script to
>>> extract the numbers to be plotted - such as the Offset in the graphs
>>> above. An easy job if the format is standardised and machine readable.
>> I based my script on yours for ntp but changed from using a
>> linear axis to log. I first used chrony on NetBSD when on
>> dialup with demon and later for a while when on broadband.
>> When I first compared chrony with ntpd there was no contest
>> but more recent experiments with chrony had periods of
>> severe instability much worse than ntpd.
> More recent means what? What version of chrony? (there was a bug found
> in the past two weeks that was introduces a few months ago which did
> result in instability)
More recent than November 2009.
Probably between Dec 2009 and Jan 2010 and p4x2400c.
>> P4X2666 with chrony
> Not at all sure what I am supposed to see. I have no idea what the graph
> axes represent? What is 1.1k
X-axis is in hours
Y-axis is offset in us so 1.1k = 1100us
Next experiment is to couple up the GPS again but if you
click on the ME6000 in the current stats the yearly graph
for Sep/Oct/Nov was when I last had the gps connected.
> Note that you can see my offsets with chrony on my web page. The network
> problems really do cause difficulty, but the offsets in general are very
> small -- 10usec over the network.
>> Current stats all with ntpd.
More information about the questions