Hello all,
i work in a web hosting compagny. We have a strange problem on many servers.
The hardware clock of several server is totaly instable. This happen on many
server, not all.
Symptoms:
root@computer:~# date && hwclock
Wed Jun 4 13:53:21 CEST 2008
Sat Jun 7 20:23:16 2008 -0.576925 seconds
root@computer:~# hwclock --systohc
root@computer:~# date && hwclock
Wed Jun 4 13:53:34 CEST 2008
Wed Jun 4 13:53:36 2008 -0.835749 seconds
(2 seconds !)
root@rd10:~# date && hwclock
Wed Jun 4 13:53:42 CEST 2008
Wed Jun 4 13:54:02 2008 -0.779573 seconds
(20 seconds !!)
I have try to pass clock or clocksource= hpet, pti to the kernel at boot: same
troubles.
Kernel information:
cat /proc/version
Linux version 2.6.24.2 (root@XXXXXXX ) (gcc version 4.1.2 20061115
(prerelease) (Debian 4.1.1-21)) #1 SMP Wed Feb 20 15:40:12 CET 2008
cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 8
model name : Pentium III (Coppermine)
stepping : 6
cpu MHz : 797.548
cache size : 256 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
cmov pat pse36 mmx fxsr sse
bogomips : 1596.12
clflush size : 32
processor : 1
vendor_id : GenuineIntel
cpu family : 6
model : 8
model name : Pentium III (Coppermine)
stepping : 6
cpu MHz : 797.548
cache size : 256 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
cmov pat pse36 mmx fxsr sse
bogomips : 1595.08
clflush size : 32
cat /proc/ioports
0000-001f : dma1
0020-0021 : pic1
0040-0043 : timer0
0050-0053 : timer1
0060-006f : keyboard
0070-0077 : rtc
0080-008f : dma page reg
00a0-00a1 : pic2
00c0-00df : dma2
00f0-00ff : fpu
0170-0177 : 0000:00:0f.1
01f0-01f7 : 0000:00:0f.1
01f0-01f7 : ide0
0220-0223 : ACPI PM1a_EVT_BLK
0230-0231 : ACPI PM1a_CNT_BLK
0240-0243 : ACPI PM_TMR
02f8-02ff : serial
0376-0376 : 0000:00:0f.1
03c0-03df : vga+
03f2-03f5 : floppy
03f6-03f6 : 0000:00:0f.1
03f6-03f6 : ide0
03f7-03f7 : floppy DIR
03f8-03ff : serial
0408-040f : pnp 00:01
0cf8-0cff : PCI conf1
0f50-0f58 : pnp 00:01
1800-18ff : 0000:00:04.0
2000-20ff : 0000:00:01.0
2000-20ff : cpqarray
2400-243f : 0000:00:02.0
2400-243f : e100
2800-28ff : 0000:00:03.0
2c00-2c0f : 0000:00:0f.1
cat /proc/iomem
00000000-0009f7ff : System RAM
0009f800-0009ffff : reserved
000a0000-000bffff : Video RAM area
000c0000-000c7fff : Video ROM
000e8000-000edfff : Adapter ROM
000f0000-000fffff : System ROM
00100000-1fffbfff : System RAM
00200000-005c7a77 : Kernel code
005c7a78-00717f7b : Kernel data
0075e000-007cfbc7 : Kernel bss
1fffc000-1fffffff : ACPI Tables
30000000-300fffff : 0000:00:02.0
30100000-3017ffff : 0000:00:01.0
30180000-3019ffff : 0000:00:03.0
c3000000-c3ffffff : 0000:00:03.0
c4dfef00-c4dfefff : 0000:00:04.0
c4dff000-c4dfffff : 0000:00:03.0
c4e00000-c4efffff : 0000:00:02.0
c4e00000-c4efffff : e100
c4fff000-c4ffffff : 0000:00:02.0
c4fff000-c4ffffff : e100
c5000000-c5ffffff : 0000:00:01.0
c6000000-c6ffffff : 0000:00:01.0
fec00000-fec0ffff : reserved
fee00000-fee0ffff : reserved
fff80000-ffffffff : reserved
lspci -vvvv
00:00.0 Host bridge: Broadcom CNB20LE Host Bridge (rev 06)
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR+ FastB2B-
Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort+ >SERR- <PERR-
Latency: 64, Cache Line Size: 32 bytes
00:00.1 Host bridge: Broadcom CNB20LE Host Bridge (rev 06)
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR+ FastB2B-
Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR-
Latency: 64, Cache Line Size: 32 bytes
00:01.0 RAID bus controller: LSI Logic / Symbios Logic 53C1510 (rev 02)
Subsystem: Compaq Computer Corporation Integrated Array Controller
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV+ VGASnoop- ParErr-
Stepping- SERR+ FastB2B-
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR-
Latency: 192 (7500ns min, 2000ns max), Cache Line Size: 32 bytes
Interrupt: pin A routed to IRQ 16
Region 0: I/O ports at 2000 [size=256]
Region 1: Memory at c6000000 (32-bit, non-prefetchable) [size=16M]
Region 2: Memory at c5000000 (32-bit, non-prefetchable) [size=16M]
[virtual] Expansion ROM at 30100000 [disabled] [size=512K]
Capabilities: [40] Power Management version 2
Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA
PME(D0-,D1-,D2-,D3hot-,D3cold-)
Status: D0 PME-Enable- DSel=0 DScale=0 PME-
00:02.0 Ethernet controller: Intel Corporation 82557/8/9 [Ethernet Pro 100]
(rev 08)
Subsystem: Compaq Computer Corporation NC3163 Fast Ethernet NIC
(embedded, WOL)
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV+ VGASnoop- ParErr-
Stepping- SERR+ FastB2B-
Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR-
Latency: 64 (2000ns min, 14000ns max), Cache Line Size: 32 bytes
Interrupt: pin A routed to IRQ 17
Region 0: Memory at c4fff000 (32-bit, non-prefetchable) [size=4K]
Region 1: I/O ports at 2400 [size=64]
Region 2: Memory at c4e00000 (32-bit, non-prefetchable) [size=1M]
[virtual] Expansion ROM at 30000000 [disabled] [size=1M]
Capabilities: [dc] Power Management version 2
Flags: PMEClk- DSI+ D1+ D2+ AuxCurrent=0mA
PME(D0+,D1+,D2+,D3hot+,D3cold+)
Status: D0 PME-Enable- DSel=0 DScale=2 PME-
00:03.0 VGA compatible controller: ATI Technologies Inc 3D Rage IIC 215IIC
[Mach64 GT IIC] (rev 7a) (prog-if 00 [VGA])
Subsystem: ATI Technologies Inc Rage IIC
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping+ SERR- FastB2B-
Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR-
Latency: 64 (2000ns min), Cache Line Size: 32 bytes
Region 0: Memory at c3000000 (32-bit, prefetchable) [size=16M]
Region 1: I/O ports at 2800 [size=256]
Region 2: Memory at c4dff000 (32-bit, non-prefetchable) [size=4K]
[virtual] Expansion ROM at 30180000 [disabled] [size=128K]
Capabilities: [5c] Power Management version 1
Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA
PME(D0-,D1-,D2-,D3hot-,D3cold-)
Status: D0 PME-Enable- DSel=0 DScale=0 PME-
00:04.0 System peripheral: Compaq Computer Corporation Advanced System
Management Controller
Subsystem: Compaq Computer Corporation Unknown device b0f3
Control: I/O+ Mem+ BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR+ FastB2B-
Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR-
Interrupt: pin A routed to IRQ 255
Region 0: I/O ports at 1800 [size=256]
Region 1: Memory at c4dfef00 (32-bit, non-prefetchable) [size=256]
00:0f.0 ISA bridge: Broadcom OSB4 South Bridge (rev 51)
Subsystem: Broadcom OSB4 South Bridge
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR- FastB2B-
Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR-
Latency: 0
00:0f.1 IDE interface: Broadcom OSB4 IDE Controller (prog-if 8a [Master SecP
PriP])
Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR+ FastB2B-
Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR-
Latency: 64
Region 0: [virtual] Memory at 000001f0 (32-bit, non-prefetchable)
[disabled] [size=8]
Region 1: [virtual] Memory at 000003f0 (type 3, non-prefetchable)
[disabled] [size=1]
Region 2: [virtual] Memory at 00000170 (32-bit, non-prefetchable)
[disabled] [size=8]
Region 3: [virtual] Memory at 00000370 (type 3, non-prefetchable)
[disabled] [size=1]
Region 4: I/O ports at 2c00 [size=16]
On Wed, Jun 4, 2008 at 2:02 PM, Lkm <[email protected]> wrote:
>
> i work in a web hosting compagny. We have a strange problem on many servers.
> The hardware clock of several server is totaly instable. This happen on many
> server, not all.
Which messages are logged by the NTP daemon during the first 24 hours
after it has been started ? On Debian systems you can install NTP by
running apt-get install ntp.
Bart.
Le Wednesday 04 June 2008 14:49:58 Bart Van Assche, vous avez ?crit?:
> On Wed, Jun 4, 2008 at 2:02 PM, Lkm <[email protected]> wrote:
> > i work in a web hosting compagny. We have a strange problem on many
> > servers. The hardware clock of several server is totaly instable. This
> > happen on many server, not all.
>
> Which messages are logged by the NTP daemon during the first 24 hours
> after it has been started ? On Debian systems you can install NTP by
> running apt-get install ntp.
>
> Bart.
Ntpd logs:
28 May 10:32:17 ntpd[31086]: synchronized to 192.168.0.150, stratum 3
28 May 10:51:34 ntpd[31086]: synchronized to 192.168.0.151, stratum 3
29 May 00:20:57 ntpd[31086]: synchronized to 192.168.0.150, stratum 3
29 May 01:46:28 ntpd[31086]: synchronized to 192.168.0.151, stratum 3
29 May 02:27:10 ntpd[31086]: synchronized to 192.168.0.150, stratum 3
29 May 02:33:34 ntpd[31086]: synchronized to 192.168.0.151, stratum 3
29 May 02:39:02 ntpd[31086]: synchronized to 192.168.0.150, stratum 3
29 May 04:02:28 ntpd[31086]: synchronized to 192.168.0.151, stratum 3
29 May 04:45:12 ntpd[31086]: synchronized to 192.168.0.150, stratum 3
29 May 09:01:20 ntpd[31086]: synchronized to 192.168.0.151, stratum 3
31 May 16:16:55 ntpd[31086]: synchronized to 192.168.0.150, stratum 3
31 May 17:33:50 ntpd[31086]: synchronized to 192.168.0.151, stratum 3
31 May 17:59:26 ntpd[31086]: synchronized to 192.168.0.150, stratum 3
31 May 18:33:32 ntpd[31086]: synchronized to 192.168.0.151, stratum 3
31 May 18:47:22 ntpd[31086]: synchronized to 192.168.0.150, stratum 3
31 May 18:52:04 ntpd[31086]: synchronized to 192.168.0.151, stratum 3
31 May 18:55:53 ntpd[31086]: synchronized to 192.168.0.150, stratum 3
31 May 19:49:25 ntpd[31086]: synchronized to 192.168.0.151, stratum 3
31 May 20:28:30 ntpd[31086]: synchronized to 192.168.0.150, stratum 3
31 May 21:45:19 ntpd[31086]: synchronized to 192.168.0.151, stratum 3
2 Jun 05:28:59 ntpd[31086]: synchronized to 192.168.0.150, stratum 3
2 Jun 10:46:26 ntpd[31086]: ntpd exiting on signal 15
2 Jun 10:53:32 ntpd[2299]: synchronized to 192.168.0.150, stratum 3
2 Jun 10:53:32 ntpd[2299]: kernel time sync enabled 0001
2 Jun 11:02:11 ntpd[2299]: synchronized to 192.168.0.151, stratum 3
2 Jun 11:06:36 ntpd[2299]: synchronized to 192.168.0.150, stratum 3
2 Jun 11:19:26 ntpd[2299]: synchronized to 192.168.0.151, stratum 3
2 Jun 11:55:56 ntpd[2299]: synchronized to 192.168.0.150, stratum 3
2 Jun 12:34:24 ntpd[2299]: synchronized to 192.168.0.151, stratum 3
2 Jun 13:00:08 ntpd[2299]: synchronized to 192.168.0.150, stratum 3
2 Jun 13:33:44 ntpd[2299]: ntpd exiting on signal 15
2 Jun 13:42:20 ntpd[2299]: synchronized to 192.168.0.150, stratum 3
2 Jun 13:42:20 ntpd[2299]: time reset -109.498922 s
2 Jun 13:42:20 ntpd[2299]: kernel time sync enabled 0001
2 Jun 13:45:34 ntpd[2299]: synchronized to 192.168.0.151, stratum 3
2 Jun 14:21:59 ntpd[2299]: synchronized to 192.168.0.150, stratum 3
2 Jun 14:30:41 ntpd[2299]: synchronized to 192.168.0.151, stratum 3
2 Jun 15:33:28 ntpd[2299]: ntpd exiting on signal 15
2 Jun 15:39:55 ntpd[2300]: ntpd exiting on signal 15
2 Jun 15:46:39 ntpd[2354]: synchronized to 192.168.0.150, stratum 3
2 Jun 15:46:39 ntpd[2354]: kernel time sync enabled 0001
2 Jun 15:54:11 ntpd[2354]: synchronized to 192.168.0.151, stratum 3
2 Jun 15:59:36 ntpd[2354]: synchronized to 192.168.0.150, stratum 3
2 Jun 16:27:25 ntpd[2354]: synchronized to 192.168.0.151, stratum 3
2 Jun 16:36:06 ntpd[2354]: synchronized to 192.168.0.150, stratum 3
2 Jun 17:01:40 ntpd[2354]: synchronized to 192.168.0.151, stratum 3
2 Jun 17:50:52 ntpd[2354]: synchronized to 192.168.0.150, stratum 3
3 Jun 01:31:52 ntpd[2354]: synchronized to 192.168.0.151, stratum 3
Other (useful?) logs:
Jun 4 14:29:53 rd10 kernel: set_rtc_mmss: can't update from 77 to 29
Jun 4 14:29:54 rd10 kernel: set_rtc_mmss: can't update from 77 to 29
Jun 4 14:29:55 rd10 kernel: set_rtc_mmss: can't update from 77 to 29
Jun 4 14:29:56 rd10 kernel: set_rtc_mmss: can't update from 77 to 29
Jun 4 14:29:57 rd10 kernel: set_rtc_mmss: can't update from 77 to 29
Jun 4 14:29:58 rd10 kernel: set_rtc_mmss: can't update from 77 to 29
Jun 4 14:29:59 rd10 kernel: set_rtc_mmss: can't update from 77 to 29
Jun 4 14:30:00 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:01 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:02 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:03 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:04 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:05 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:06 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:07 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:08 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:09 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:10 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:11 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:12 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:13 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:14 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:15 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:16 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:17 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:18 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:19 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:20 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:21 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:22 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:23 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:24 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:25 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:26 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:27 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:28 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:29 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:30 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:31 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:32 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:33 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:34 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:35 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:36 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:37 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:38 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:39 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:40 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:41 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:42 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:43 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:44 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:45 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:46 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
Jun 4 14:30:47 rd10 kernel: set_rtc_mmss: can't update from 78 to 30
:
On Wed, Jun 4, 2008 at 3:17 PM, Lkm <[email protected]> wrote:
> Ntpd logs:
...
> 2 Jun 13:42:20 ntpd[2299]: time reset -109.498922 s
...
The reason I asked for the ntpd logs is that I'm still not sure
whether there is a hardware problem. How long was the ntpd process
running when the above line was logged ? And can you also post the
output of ntpq -pn ?
Bart.
Le Wednesday 04 June 2008 15:40:49 Bart Van AsscI de, vous avez ?crit?:
> On Wed, Jun 4, 2008 at 3:17 PM, Lkm <[email protected]> wrote:
> > Ntpd logs:
>
> ...
>
> > 2 Jun 13:42:20 ntpd[2299]: time reset -109.498922 s
>
> ...
>
> The reason I asked for the ntpd logs is that I'm still not sure
> whether there is a hardware problem.
In fact i'm wondering too .... But we have so many server with the same
problem...
> How long was the ntpd process
> running when the above line was logged ?
I have rebooted the server on Mon Jun 2 13:37 (show in last command) for
testing clock and clocksource boot argument.
If i look forward in the log:
26 Feb 11:25:12 ntpd[2422]: time reset -0.492486 s
I Don't know if we have rebooted the server this day..
> And can you also post the
> output of ntpq -pn ?
>
ntpq -pn
remote refid st t when poll reach delay offset jitter
==============================================================================
+192.168.0.150 195.220.194.193 3 u 531 1024 377 1.398 0.606 0.402
*192.168.0.151 194.2.0.28 3 u 399 1024 377 0.554 0.426 0.172
> Bart.
On Wed, Jun 4, 2008 at 4:22 PM, Lkm <[email protected]> wrote:
> Le Wednesday 04 June 2008 15:40:49 Bart Van AsscI de, vous avez ?crit :
>> The reason I asked for the ntpd logs is that I'm still not sure
>> whether there is a hardware problem.
>
> In fact i'm wondering too .... But we have so many server with the same
> problem...
...
> 26 Feb 11:25:12 ntpd[2422]: time reset -0.492486 s
> I Don't know if we have rebooted the server this day..
A "time reset" can happen for one of three reasons:
* as a startup phenomenon (ntpd's frequency estimate is still converging).
* because of a step in the reference clock.
* because of instability of the hardware clock. Personally I have not
yet seen this.
>> And can you also post the
>> output of ntpq -pn ?
>>
> ntpq -pn
> remote refid st t when poll reach delay offset jitter
> ==============================================================================
> +192.168.0.150 195.220.194.193 3 u 531 1024 377 1.398 0.606 0.402
> *192.168.0.151 194.2.0.28 3 u 399 1024 377 0.554 0.426 0.172
This data looks normal -- both time servers have the same stratum,
reachability == 0377, delay and offset are below 5ms, and jitter is
below 1ms.
So I suggest that you observe the ntp logs for a few days and check
whether the ntp daemon logs any error messages.
Bart.