time drift w/virtualbox: FreeBSD Host -> FreeBSD guest w/ guest additions active

[Mikhail Tsatsenko]

2013/12/4 Marc Fournier <mfournier at openstudent.ca>:
>
> Why is this such a difficult thing to keep in sync? :(
>
> I have a FreeBSD Host running 4.2.18 … Guest FreeBSD Host has Additions 4.2.18 installed ..
>
> On the Host, I believe all the kernel modules are loaded properly:
>
> # kldstat|grep vb
>  6    3 0xffffffff80c59000 59da0    vboxdrv.ko
>  8    2 0xffffffff80e20000 29f1     vboxnetflt.ko
> 11    1 0xffffffff80e2e000 3f8a     vboxnetadp.ko
>
> On the Guest, again, I believe everything is loaded:
>
> # kldstat|grep vb
>  2    1 0xffffffff80c12000 26585    vboxguest.ko
>
> And the VB processes are started:
>
> # ps aux | grep VB
> root      606  0.0  0.1  32244   2144 ??  Ss    6:06PM    2:09.26 /usr/local/sbin/VBoxService
>
> I don’t have ntpd running on the Guest, but have tried it with it running also ...
>
> But, my time is already drifting:
>
> # ssh ruralcatholicradio.com date ; date
> Wed Dec  4 12:01:34 EST 2013
> Wed Dec  4 17:03:17 UTC 2013
>
> So, I login and run ntpdate to bring it back in sync:
>
> # ntpdate time.nist.gov
>  4 Dec 12:04:02 ntpdate[71827]: step time server 66.219.116.140 offset 102.233151 sec
>
> Note that the below is run from the FreeBSD Host that the Guest is running on … same physical machine … we are perfectly in sync:
>
> # ssh ruralcatholicradio.com date ; date
> Wed Dec  4 12:04:32 EST 2013
> Wed Dec  4 17:04:32 UTC 2013
>
> An hour later, we’ve now drifted by almost 2 minutes:
>
> # ssh ruralcatholicradio.com date ; date
> Wed Dec  4 13:07:18 EST 2013
> Wed Dec  4 18:09:16 UTC 2013
>
>
> Its hard to believe that anyone would be using VirtualBox if it time drifted like this regularly, so I figure it has to be something that I’m doing wrong in my configuration …
>
>
> Thoughts?
Please try setting sysctl kern.eventtimer.idletick=1 on the guest machine.

-- 
Mikhail