On 2/25/2012 6:42 PM, unruh wrote:
On 2012-02-25, Richard B. Gilbert<rgilber...@comcast.net> wrote:
On 2/25/2012 1:20 AM, A C wrote:
On 2/24/2012 21:26, A C wrote:
Is it possible to change the polling interval of one or more associated
servers at runtime? It seems like I should be able to run:
ntpq -c "writevar&associd hpoll=N" or is it ppoll?
Actually, I should have been more specific and say change the minimum
polling interval. In other words, be able to adjust the conf file's
minpoll flag at runtime instead of restarting.
What problem are you trying to solve?
NTPD does a pretty good job of adjusting itself most of the time.
Short poll intervals are useful when correcting large errors.
Long poll intervals allow NTPD to make small corrections very accurately.
IF the drift is very stable, long poll intervals allow ntpd to make
small corrections to the drift rate accurately. They in general make the
offsets larger and mean that the system cannot respond to changes (eg
temp changes due to the coputer being used) rapidly. This is especially
true of ntpd because it throws away 7/8 of the measurements in the clock
filter, meaning that the actuall poll time is about 8 times longer than
the set poll interval. (poll 10 then has an effective poll of 8000 sec)
Anyway, that is an aside. I agree with you that I do not understand what
problem he is trying to solve.
I'll admit to not having read every sentence in this thread, but I have
a question about what was just said. Even if the clock algorithm
discards 7/8 of the measurements, as stated, isn't ntpd sitll hitting
the remote servers at whatever the minpoll value is set to, or the
default minpoll value if not set. So, if the internet servers are set
to a minpoll value of 8 (approximately 4 minutes), aren't those remote
servers actually getting polled every 4 minutes, regardless of what ntpd
does with the data.
Sincerely,
Ron
--
(PS - If you email me and don't get a quick response, don't be concerned.
I get about 300 emails per day from alternate energy mailing lists and
such. I don't always see new messages very quickly. If you need a
reply and have not heard from me in 1 - 2 weeks, send your message again.)
Ron Frazier
timekeepingdude AT c3energy.com
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