unruh wrote:
On 2010-07-26, Thierry MARTIN <[email protected]> wrote:
On 26 juil, 16:39, unruh <[email protected]> wrote:
On 2010-07-26, Thierry MARTIN <[email protected]> wrote:
Hello,
Is there any API that can be used in a program to be "notified" if a
"step time server" event occurs?
As far as I could see, it is "only" logged.
You could have something read the logs and notify your program. Or if
you are on Linux/BSD you could run chrony, which does not step.
Mind you if ntpd is stepping after having been running for a few hours,
something is seriously wrong, and needs fixing.
Thanks in advance for your answers.
/ Thierry
Unfortunately, watching the logs does not fit my need.
I will try and explain what are my constraints.
My program is doing network packet acquisition on several links and
needs to sort them - based on the timestamps.
Also, many network measurements are very badly affected by time
stepping forward or backward.
This explains why I'd like to be notified of time steps. (It is easy
when time is going backward, but not in the other case).
I think ntpd ajusts time by step if the system looses connection to
ntp sources for a while (I set up the step threshold to 1s on the ntp
server).
No. ntpd steps if the time is out xby more than 125ms. This is a failure
of ntpd, but it is NOT something that should happen.
Your clocks should not step even if they loose connectivity for a fair
while if their frequency has been disciplined-- and if your network
looses connectivity, then your network monitoring is screwed anyway.
You might also want to let the clock freewheel (ie do not use ntp to
discipline it) but use ntp to find out how far out your clocks actually
are. Then again you can use that info to correct the times of the
timestamps after the fact.
But this stepping is simply a feature of ntpd. If you do not like it,
use chrony instead (unless you are on windows).
Stepping is not exactly a "feature" of NTPD. It's a last resort for
fixing a totally screwed up clock. If your clock is off by fifteen
minutes, do you *really* want to wait three or four weeks for NTPD to
fix it "gently"?? There are a few sites that would have no choice but
to do so but they are extremely careful to avoid the necessity!
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