unruh wrote:
On 2011-04-20, David Lord <[email protected]> wrote:
unruh wrote:
On 2011-04-20, David Lord <[email protected]> wrote:
unruh wrote:
On 2011-04-19, David Lord <[email protected]> wrote:
unruh wrote:
On 2011-04-19, David Lord <[email protected]> wrote:
.....
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.
chrony 1.23
OK well before that change.
P4X2666 with chrony
<http://www.lordynet.org.uk/mrtg/stats/>
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
WOW. What kind of network are you attached to? Even on an ADSL link
through the phone company, I
was getting in the tens of usec (not ms) as the offsets of chrony.
(checked by a gps receiver attached to the local computer).
I'm on ADSL-1 with 2 Mbit/s down and 288 kbit/s up. Latency
is what BT delivers and has been as low as 12ms up to 50ms or
more but mostly it's about 18ms to nearest sites (when exchange
gets near capacity the latency jumps up by 15ms or more same as
when interleave is enabled on ADSSL-2).
Although the peaks of the graph are at about 1ms the stats
have "System time" mostly being in the 10s of usec.
Not sure what you mean by that. What I mean is , what are the measured
offsets? (Of course if you have a GPS PPS that you could use as a
reference-- not a source of time-- that would make much clearer what is
going on.)
My logs have eg:
Reference ID : me6000g
Stratum : 2
Ref time (UTC) : Sat Jan 9 07:12:02 2010
System time : 0.000001 seconds slow of NTP time
OK, that is the kind of thing chrony should do. Ie, to discipline the
system clock to usec levels
Frequency : 0.125 ppm fast
That is a really small drift rate. Just lucky I guess.
Residual freq : -0.010 ppm
Skew : 0.223 ppm
So the frequency is really pretty stable.
Root delay : 0.001297 seconds
Root dispersion : 0.007492 seconds
That is a huge root delay and dispersion. Where are your servers?
Possibly the pc using a MSF 60kHz radioclock is preferred vs
the internet servers. Reception during December through March
can be bad. GPS is also affected by same weather conditions.
Internet connection was also bad during winter 2009/2010 with
electric and gas supplies both failing.
I've not yet checked all of the systems that were tried
with chrony but these servers are all in use so it's not
easy to just install chrony and expect it to work.
Sure it is. Just install it, configure it and start it ( switching off
ntpd first). Of course if your server is supposed to keep really good
time all the time, then this might cause some initial problems as you
switch over.
I run a couple of internet servers and added them to ntp pool
which is why I'm not keen to take risks.
David
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