[ntp:questions] What level of timesynch error is typical onWinXP?

David L. Mills mills at udel.edu
Tue Nov 2 22:03:30 UTC 2010


Miroslav,

I ran the same test here on four different machines with the expected 
results. These included Solaris on both SPARC and Intel machines, as 
well as two FreeBSD machines. I tested with and without the kernel, with 
initial offset 300 ms (including step correction) and 100 ms. I tested 
with initial poll interval of 16 s and 64 s. At 16 s, the leftover 
offset after frequency update was about half a millisecond within spec, 
but this torqued the frequency about 2 PPM as expected. It settled down 
within 1 PM within 20 m.

Bottom line; I cannot verify your experience.

Dave

Miroslav Lichvar wrote:

>On Tue, Nov 02, 2010 at 01:29:14PM +0000, David L. Mills wrote:
>  
>
>>This doesn't make any sense. Your data show the frequency set to 0.0
>>and the a series of clock steps after that. If this is with your
>>simulator, try it with the real machine. I have tested with three
>>machines herewith and without kernel and with no such problems.
>>    
>>
>
>I have now such test running on real hw as I got that suggestion on
>#ntp too. But the result is the same, the frequency estimation is
>~170ppm off, see the following log. It's running with "disable kernel"
>and the kernel frequency was left as ntpd using kernel discipline set
>it, so for the daemon loop the frequency offset would be close to 0.
>
>Again, this is with 0.1s initial offset, zero frequency offset, 64s
>polling interval and no drift file.
>
>Nov  2 12:53:08 localhost ntpd[8526]: ntpd 4.2.7p74 at 1.2307 Mon Nov  1 12:20:56 UTC 2010 (1)
>Nov  2 12:53:08 localhost ntpd[8526]: proto: precision = 0.105 usec
>Nov  2 12:53:08 localhost ntpd[8526]: Listen and drop on 0 v4wildcard 0.0.0.0 UDP 123
>Nov  2 12:53:08 localhost ntpd[8526]: Listen and drop on 1 v6wildcard :: UDP 123
>Nov  2 12:53:08 localhost ntpd[8526]: Listen normally on 2 lo 127.0.0.1 UDP 123
>Nov  2 12:53:08 localhost ntpd[8526]: Listen normally on 3 br0 10.34.24.25 UDP 123
>...
>Nov  2 12:53:08 localhost ntpd[8526]: Listen normally on 10 lo ::1 UDP 123
>Nov  2 12:53:08 localhost ntpd[8526]: 10.34.32.125 8011 81 mobilize assoc 11921
>Nov  2 12:53:08 localhost ntpd[8526]: 0.0.0.0 c016 06 restart
>Nov  2 12:53:08 localhost ntpd[8526]: 0.0.0.0 c012 02 freq_set ntpd 0.000 PPM
>Nov  2 12:53:08 localhost ntpd[8526]: 0.0.0.0 c011 01 freq_not_set
>Nov  2 12:53:09 localhost ntpd[8526]: 10.34.32.125 8024 84 reachable
>Nov  2 12:56:21 localhost ntpd[8526]: 10.34.32.125 963a 8a sys_peer
>Nov  2 12:56:21 localhost ntpd[8526]: 0.0.0.0 c614 04 freq_mode
>Nov  2 13:01:44 localhost ntpd[8526]: 0.0.0.0 0612 02 freq_set ntpd 172.556 PPM
>Nov  2 13:01:44 localhost ntpd[8526]: 0.0.0.0 0615 05 clock_sync
>Nov  2 13:20:18 localhost ntpd[8526]: 0.0.0.0 0613 03 spike_detect -0.138466 s
>Nov  2 13:29:04 localhost ntpd[8526]: 0.0.0.0 061c 0c clock_step -0.144407 s
>Nov  2 13:29:04 localhost ntpd[8526]: 0.0.0.0 0615 05 clock_sync
>Nov  2 13:29:05 localhost ntpd[8526]: 0.0.0.0 c618 08 no_sys_peer
>Nov  2 13:29:05 localhost ntpd[8526]: 10.34.32.125 8044 84 reachable
>Nov  2 13:35:47 localhost ntpd[8526]: 10.34.32.125 965a 8a sys_peer
>Nov  2 13:44:45 localhost ntpd[8526]: 0.0.0.0 0613 03 spike_detect -0.152547 s
>Nov  2 13:49:09 localhost ntpd[8526]: 0.0.0.0 061c 0c clock_step -0.177271 s
>Nov  2 13:49:09 localhost ntpd[8526]: 0.0.0.0 0615 05 clock_sync
>Nov  2 13:49:10 localhost ntpd[8526]: 0.0.0.0 c618 08 no_sys_peer
>Nov  2 13:49:10 localhost ntpd[8526]: 10.34.32.125 8064 84 reachable
>Nov  2 13:57:07 localhost ntpd[8526]: 10.34.32.125 967a 8a sys_peer
>Nov  2 14:09:12 localhost ntpd[8526]: 0.0.0.0 0613 03 spike_detect -0.130677 s
>Nov  2 14:15:45 localhost ntpd[8526]: 0.0.0.0 061c 0c clock_step -0.180840 s
>Nov  2 14:15:45 localhost ntpd[8526]: 0.0.0.0 0615 05 clock_sync
>Nov  2 14:15:46 localhost ntpd[8526]: 0.0.0.0 c618 08 no_sys_peer
>Nov  2 14:15:46 localhost ntpd[8526]: 10.34.32.125 8084 84 reachable
>Nov  2 14:21:22 localhost ntpd[8526]: 10.34.32.125 969a 8a sys_peer
>Nov  2 14:32:30 localhost ntpd[8526]: 0.0.0.0 0613 03 spike_detect -0.131304 s
>Nov  2 14:37:54 localhost ntpd[8526]: 0.0.0.0 061c 0c clock_step -0.155809 s
>Nov  2 14:37:54 localhost ntpd[8526]: 0.0.0.0 0615 05 clock_sync
>Nov  2 14:37:55 localhost ntpd[8526]: 0.0.0.0 c618 08 no_sys_peer
>Nov  2 14:37:55 localhost ntpd[8526]: 10.34.32.125 80a4 84 reachable
>Nov  2 14:49:16 localhost ntpd[8526]: 10.34.32.125 96ba 8a sys_peer
>
>
>
>  
>




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