| Re: [chrony-dev] Time for a release? |
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On Thu, 7 Oct 2010, Miroslav Lichvar wrote:
On Thu, Oct 07, 2010 at 09:02:56AM -0700, Bill Unruh wrote:
- improve the code which adjusts the polling interval between
minpoll and maxpoll, the current one seems to work quite badly
In what sense "badly"? I looked at it for a while, but did not see how one of
the other choice would be better. What are you trying to maximize?
It uses too long intervals when jitter is low (the accuracy suffers)
and too short intervals when jitter is high (wasting network
bandwidth).
The most promising idea I came up so far is to adjust the interval
based on number of samples kept in sourcestats, so it remains close to
a fixed number. This would be configurable, a higher value would mean
chrony should try to keep the buffer more filled and thus have better
accuracy. The default would be set so chrony uses less or same
resources than ntpd with same minpoll and maxpoll, while keeping
better accuracy.
As far as I could see, ntpd tends to race for long intervals and stick there.
There seems to be an idea that network resources are prcious and should be
used as little as possible. Since nowadays, network resources ( unless you in
a sattelite in orbit) are essentially free, the balance seems a bit skewed.
Esp with chrony, using many measurements should always be better.
--
William G. Unruh | Canadian Institute for| Tel: +1(604)822-3273
Physics&Astronomy | Advanced Research | Fax: +1(604)822-5324
UBC, Vancouver,BC | Program in Cosmology | unruh@xxxxxxxxxxxxxx
Canada V6T 1Z1 | and Gravity | www.theory.physics.ubc.ca/
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