[pkg-ntp-maintainers] Bug#559634: no kernel sync and "ntpdc -c kerninfo" reports incorrect estimates of time on Xen dom0

[Michael Bilow]

Package: ntp
Version: 1:4.2.4p4+dfsg-8lenny2
Severity: normal



This is taking place on Xen dom0, not domU. (The name of the server --
the Xen host -- is "virtual1".) As far as I understand, ntp should work
normally on dom0.

I have no actual evidence that ntp is synchronizing the clock at all.

Although wall time (from "date") is quite accurate as well as I can
visually estimate, the "maximum error" and "estimated error" reported
from "ntpdc -c kerninfo" are what would be seen when the ntp server is
totally unsynchronized:


virtual1:~$ date
Sat Dec  5 14:35:06 EST 2009

virtual1:~$ ntpdc -c kerninfo
pll offset:           0 s
pll frequency:        0.690 ppm
maximum error:        16 s
estimated error:      16 s
status:               0041  pll unsync
pll time constant:    6
precision:            1e-06 s
frequency tolerance:  500 ppm

virtual1:~$ date
Sat Dec  5 14:35:12 EST 2009


Although "ntpdc -c sysinfo" indicates kernel sync, "reference time" can
be a number of seconds off; this could be a Xen issue but I don't know:


virtual1:~$ date
Sat Dec  5 14:36:54 EST 2009

virtual1:~$ ntpdc -c sysinfo
system peer:          navobs1.gatech.edu
system peer mode:     client
leap indicator:       00
stratum:              2
precision:            -20
root distance:        0.02779 s
root dispersion:      0.04031 s
reference ID:         [130.207.244.240]
reference time:       cec534c9.702c7f40  Sat, Dec  5 2009 14:36:41.438
system flags:         auth monitor ntp kernel stats
jitter:               0.007736 s
stability:            0.000 ppm
broadcastdelay:       0.003998 s
authdelay:            0.000007 s

virtual1:~$ date
Sat Dec  5 14:36:57 EST 2009


Offsets reported against known good servers; the last four are just
random selections from the Debian pool:


virtual1:~$ date
Sat Dec  5 14:40:15 EST 2009

virtual1:~$ ntpq -p
      remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
  ns.intap.net    .STEP.          16 u    -   64    0    0.000    0.000   0.000
  NAVOBS1.MIT.EDU .STEP.          16 u    - 1024    0    0.000    0.000   0.000
+navobs1.wustl.e .GPS.            1 u   20   64  377   30.794   38.355   4.201
*navobs1.gatech. .FLY.            1 u   19   64  377   27.873   35.955   3.669
+time-a.nist.gov .ACTS.           1 u   41   64  357   36.943   47.231   7.671
xis.phreaki.com  64.6.144.6       3 u   43   64  377    6.465  -11.939 305.046
-mustang.empire. 192.5.41.209     2 u   16   64  377   14.839   26.922   3.860
-66-96-98-9.ccup 204.9.54.119     2 u   26   64  377   36.962   21.800   5.750
-64.73.32.134    7.8.171.182      2 u   18   64  377   39.925   47.031   6.542

virtual1:~$ date
Sat Dec  5 14:40:17 EST 2009


There are four identical CPU cores shown in /proc/cpuinfo; here is 0:


processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      : Intel(R) Xeon(TM) CPU 2.80GHz
stepping        : 1
cpu MHz         : 2793.140
cache size      : 1024 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu de tsc msr pae cx8 apic mtrr cmov pat clflush acpi mmx fxsr sse sse2 ss ht nx constant_tsc pni cid
bogomips        : 5591.23
clflush size    : 64
power management:


-- System Information:
Debian Release: 5.0.3
   APT prefers stable
   APT policy: (500, 'stable')
Architecture: i386 (i686)

Kernel: Linux 2.6.26-2-xen-686 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages ntp depends on:
ii  adduser                 3.110            add and remove users and groups
ii  libc6                   2.7-18           GNU C Library: Shared libraries
ii  libcap1                 1:1.10-14        support for getting/setting POSIX.
ii  libedit2                2.11~20080614-1  BSD editline and history libraries
ii  libncurses5             5.7+20081213-1   shared libraries for terminal hand
ii  libssl0.9.8             0.9.8g-15+lenny5 SSL shared libraries
ii  lsb-base                3.2-20           Linux Standard Base 3.2 init scrip
ii  netbase                 4.34             Basic TCP/IP networking system

Versions of packages ntp recommends:
ii  perl                     5.10.0-19lenny2 Larry Wall's Practical Extraction

Versions of packages ntp suggests:
pn  ntp-doc<none>      (no description available)

-- no debconf information