In ntp.conf(5), there is a wrong description:
The argument becomes the new value for the minimum Allan
intercept, which is a parameter of the PLL/FLL clock dis-
cipline algorithm. The value in log2 seconds defaults to
7 (1024 s), which is also the lower limit.
Yes. log2(1024) is not 7, but 10. There is also the same description
in /usr/share/doc/ntp/miscopt.html, and they have been obsoleted.
=46rom ntp-4.2.0 (currently contributed in FreeBSD) and later,
this variable "allan" is set a real number (not an exponential number)
and defaults to 1500.
The default value is defined in src/contrib/ntp/ntpd/ntp_loopfilter.c.
The old version (ntp-4.1.2) was:
#define CLOCK_ALLAN 10 /* min Allan intercept (log2 s) */
and the recent version (ntp-4.2.0 and later) is:
#define CLOCK_ALLAN 1500. /* compromise Allan intercept (s) */
The description has fixed in ntp-4.2.2:
The argument becomes the new value for the Allan
intercept, which is a parameter of the PLL/FLL clock
discipline algorithm. The value is in seconds with
default 1500 s, which is appropriate for most computer
Fix: Here is a patch for CURRENT.
How-To-Repeat: man ntp.conf
roberto maintains NTP. The ntp.conf.5 change may be applied now; however,
the change to miscopt.html would take the file from the vendor branch. Assign
For bugs matching the following criteria:
Status: In Progress Changed: (is less than) 2014-06-01
Reset to default assignee and clear in-progress tags.
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