bin/156484: ntpd regularly flips between PLL and FLL mode (time sync status change 6001/2001)

[Jeremy Chadwick]

>Number:         156484
>Category:       bin
>Synopsis:       ntpd regularly flips between PLL and FLL mode (time sync status change 6001/2001)
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Apr 18 22:40:07 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator:     Jeremy Chadwick
>Release:        FreeBSD 8.2-STABLE amd64
>Organization:
>Environment:
System: FreeBSD icarus.home.lan 8.2-STABLE FreeBSD 8.2-STABLE #0: Thu Mar 24 04:21:44 PDT 2011 root at icarus.home.lan:/usr/obj/usr/src/sys/X7SBA_RELENG_8_amd64 amd64
>Description:
	ntpd on FreeBSD machines, including that on RELENG_8 source dated
	in March 2011 (ntpd 4.2.4p5), regularly flips between PLL
	and FLL mode.  This can be seen in one's log files as such:

Apr 15 14:36:14 ra ntpd[946]: kernel time sync status change 6001
Apr 15 15:01:53 ra ntpd[946]: kernel time sync status change 2001

	I'm seeing this on literally all production servers which sync
	off of public time sources.  Servers which sync off of local
	time sources (stratum 3) do not see the problem, but I doubt
	that's of any relevancy.

	These logging messages were disabled in the most recent version
	of ntpd-dev according to the official NTP developers (see
	comment #10):

	http://bugs.ntp.org/show_bug.cgi?id=452

	Using "maxpoll 9" as a workaround, which was proposed in 2006,
	also does not solve the problem, but does decrease the regularity
	of it:

	http://lists.freebsd.org/pipermail/freebsd-stable/2006-December/031512.html
>How-To-Repeat:
	n/a
>Fix:
	Given that this annoyance has existed for many years now, can we
	please work on getting the most recent ntpd into FreeBSD?

	The latest stable build is 4.2.6p3, but I don't know if this
	removes the printing of the messages or not (see bugs.ntp.org
	URL, comment #5).  Someone would need to review the source code.
>Release-Note:
>Audit-Trail:
>Unformatted: