[ntp:questions] Change poll interval at runtime?

Ron Frazier (NTP) timekeepingntplist at c3energy.com
Sun Feb 26 05:55:12 UTC 2012

On 2/25/2012 5:05 PM, A C wrote:
> On 2/25/2012 13:09, Richard B. Gilbert 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.
> The idea was to bump up the minimum poll interval after ntpd has been 
> running for a day or so to something more kind to the remote servers 
> because the refclock is holding the remote servers clamped to 64 
> seconds.  If I set minpoll in the config file, then ntpd's start up 
> takes a long time because of a long poll interval.  If I don't set the 
> minpoll, then ntpd doesn't do "a pretty good job" because it clamps 
> the polling interval.

I've noticed the same thing.  You could try what I'm doing, although I'm 
still testing for the best configuration.

# GPS Lines
server                prefer minpoll 3 maxpoll 6 mode 72
fudge time2 0.3100 refid GPS1

# Internet server lines
# NIST New York
server nist1-ny.ustiming.org              minpoll 8 maxpoll 13

# other internet server lines similar




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Ron Frazier
timekeepingdude AT c3energy.com

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