The issue I'm about to bring up has been discussed back in 2005,
but from what I've read, no solution was ever found:
http://lists.freebsd.org/pipermail/freebsd-stable/2005-April/013399.html
On multi-CPU boxes with SMP enabled in the kernel, ntpd continually
flips between PLL and FLL mode. Now, this can be normal from what
I've read... except ntpd isn't bothering to sync the clock until a
reboot.
Sep 26 15:19:39 icarus ntpd[618]: ntpd 4.2.0-a Fri Sep 22 15:40:03 PDT 2006 (1)
Sep 26 15:19:39 icarus ntpd[618]: no IPv6 interfaces found
Sep 26 15:19:47 icarus ntpd[618]: time reset +0.978246 s
Sep 26 15:19:47 icarus ntpd[618]: kernel time sync disabled 2041
Sep 26 15:21:01 icarus ntpd[618]: kernel time sync enabled 2001
Sep 26 21:42:28 icarus ntpd[618]: kernel time sync enabled 6001
Sep 26 22:16:35 icarus ntpd[618]: kernel time sync enabled 2001
Sep 27 00:16:10 icarus ntpd[618]: kernel time sync enabled 6001
Sep 27 00:33:13 icarus ntpd[618]: kernel time sync enabled 2001
{lather rinse repeat quite a few many times at random intervals}
Oct 2 02:21:16 icarus ntpd[618]: kernel time sync enabled 6001
Oct 2 02:38:20 icarus ntpd[618]: kernel time sync enabled 2001
Oct 2 08:36:42 icarus ntpd[618]: kernel time sync enabled 6001
Oct 2 08:53:46 icarus ntpd[618]: kernel time sync enabled 2001
Oct 2 11:00:37 icarus ntpd[616]: ntpd 4.2.0-a Mon Oct 2 09:14:48 PDT 2006 (1)
Oct 2 11:00:37 icarus ntpd[616]: no IPv6 interfaces found
Oct 2 11:01:09 icarus ntpd[616]: time reset +18.774392 s
Oct 2 11:01:09 icarus ntpd[616]: kernel time sync disabled 2041
Oct 2 11:02:27 icarus ntpd[616]: kernel time sync enabled 2001
As can be seen here, over a course of 6 days, the clock skewed
nearly 19 seconds. Someone please correct me if I'm wrong (I
am in no way an NTP expert), but normally clock adjustments
are logged via syslog as "time reset" entries, yes?
I do not get any "synchronisation lost" messages either,
so ntpd is able to speak to the upstream stratum server OK.
$ grep "time reset" /var/log/messages
Sep 26 15:08:58 icarus ntpd[619]: time reset +0.887500 s
Sep 26 15:11:25 icarus ntpd[619]: time reset +0.881559 s
Sep 26 15:19:47 icarus ntpd[618]: time reset +0.978246 s
Oct 2 11:01:09 icarus ntpd[616]: time reset +18.774392 s
I've tried setting the local system clock (RTC) to UTC, which
made no difference (it was PDT (GMT-0700) prior). It's
presently set to UTC.
This problem *does not* happen with a UP (non-SMP) kernel.
I have not tried disabling ACPI.
Applicable sysctls:
kern.timecounter.stepwarnings: 0
kern.timecounter.nbinuptime: 477443
kern.timecounter.nnanouptime: 0
kern.timecounter.nmicrouptime: 1033
kern.timecounter.nbintime: 40910
kern.timecounter.nnanotime: 4408
kern.timecounter.nmicrotime: 35827
kern.timecounter.ngetbinuptime: 1432
kern.timecounter.ngetnanouptime: 1170
kern.timecounter.ngetmicrouptime: 103790
kern.timecounter.ngetbintime: 0
kern.timecounter.ngetnanotime: 0
kern.timecounter.ngetmicrotime: 131615
kern.timecounter.nsetclock: 3
kern.timecounter.hardware: ACPI-fast
kern.timecounter.choice: TSC(-100) ACPI-fast(1000) i8254(0) dummy(-1000000)
kern.timecounter.tick: 1
kern.timecounter.smp_tsc: 0
rc.conf stuff:
ntpd_enable="yes"
ntpd_flags="${ntpd_flags} -g -N"
Process runs as:
/usr/sbin/ntpd -c /etc/ntp.conf -p /var/run/ntpd.pid -f /var/db/ntpd.drift -g -N
ntp.conf:
# clock.isc.org
# clepsydra.dec.com
server 204.152.184.72 iburst
server 204.123.2.5
# Default: ignore all ntp queries from ALL other hosts
restrict default ignore
# Allow queries to/from the NTP hosts listed in "server" lines
restrict 216.218.192.202 mask 255.255.255.255
restrict 216.218.254.202 mask 255.255.255.255
restrict 204.152.184.72 mask 255.255.255.255
restrict 204.123.2.5 mask 255.255.255.255
# Allow queries to/from localhost, used for ntpdc and other utils
restrict 127.0.0.0 mask 255.0.0.0
# Allow queries to/from the local private network
restrict 192.168.1.0 mask 255.255.255.0 nomodify
--
| Jeremy Chadwick jdc at parodius.com |
| Parodius Networking http://www.parodius.com/ |
| UNIX Systems Administrator Mountain View, CA, USA |
| Making life hard for others since 1977. PGP: 4BD6C0CB |