[ntp:questions] Win7: ntpd adjusting time backwards

Jeroen Mostert jmostert at xs4all.nl
Thu Dec 13 00:30:14 UTC 2012


On 2012-12-12 21:58, Jeroen Mostert wrote:
> Here's some loopstats from a brand new machine running Windows Server 2012:
>
> 56273 56211.040 -0.000185248 20.113 0.000065610 0.002127 8
> 56273 57117.052 0.000487392 20.115 0.000245606 0.002073 8
> 56273 57381.058 0.000771702 20.115 0.000250771 0.001958 8
> 56273 58424.072 0.000542051 20.118 0.000248229 0.001977 8
> 56273 59490.107 0.000320045 20.119 0.000245105 0.001903 8
> 56273 61613.141 0.000101314 20.120 0.000241965 0.001801 8
> 56273 62411.152 -0.000139791 20.119 0.000241858 0.001691 8
> 56273 63476.176 -0.000219043 20.118 0.000227966 0.001611 8
> 56273 65585.223 -0.000361511 20.116 0.000219111 0.001795 8
> 56273 66112.226 -0.000879125 20.114 0.000274771 0.001787 8
> 56273 66382.233 -0.000775453 20.113 0.000259625 0.001694 8
> 56273 66645.246 -0.000818638 20.112 0.000243336 0.001610 8
> 56273 68744.282 -0.000901985 20.105 0.000229520 0.002861 8
> 56273 69007.289 -0.000850863 20.105 0.000215455 0.002693 8
> 56273 69542.304 -0.000541853 20.103 0.000229247 0.002548 8
> 56273 69801.304 -0.000579627 20.103 0.000214857 0.002391 8
> 56273 70070.309 -0.000507633 20.102 0.000202585 0.002244 8
> 56273 70335.311 -0.000527417 20.102 0.000189630 0.002107 8
> 56273 72431.353 -0.000577564 20.097 0.000178267 0.002512 8
> 56273 72968.365 -0.000503697 20.096 0.000168786 0.002377 8
>
> This is syncing with Internet time through the NL NTP pool.
>
> I've set up four other machines to sync with this server, two virtual and two
> physical. The virtual machines are running NT 6.0, the physical machines 6.1
> (client/server flavors not relevant here). The virtuals do not have the
> multimedia timer enabled, since I've read that this can negatively affect
> performance of the host (which makes sense, since driving all virtuals with 1000
> interrupts/sec can't be easy). Even so, ntpd achieves sub-millisecond sync with
> the local server on all of them almost all of the time. I've registered three
> spikes on the virtual machines so far, of 2, 5 and 10 ms.
>
VM #1:

56273 85876.796 0.000018374 50.694 0.000021662 0.002233 4
56273 86004.805 0.000008291 50.695 0.000020574 0.002119 4
56273 86052.822 0.000033144 50.696 0.000021156 0.002054 4
56273 86180.829 -0.000007628 50.695 0.000024483 0.001949 4
56273 86196.829 0.000020398 50.696 0.000024953 0.001827 4
56273 86260.831 0.000005560 50.696 0.000023924 0.001713 4
56273 86388.856 0.000038796 50.701 0.000025276 0.002317 4

VM #2:

56273 85960.089 0.000015957 50.623 0.000131482 0.005627 4
56273 86039.794 0.000027317 50.625 0.000123056 0.005314 4
56273 86167.801 0.000089203 50.636 0.000117169 0.006288 4
56273 86183.801 0.000108884 50.637 0.000109822 0.005911 4
56273 86199.807 0.000062115 50.638 0.000104051 0.005539 4
56273 86327.809 0.000041898 50.644 0.000097593 0.005488 4
56273 86343.811 0.000038536 50.644 0.000091298 0.005138 4
56273 86375.811 0.000047414 50.646 0.000085459 0.004833 4

I mean, seriously, wow. This is just begging for some high accuracy timestamp 
reading.

-- 
J.



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