Clock lagging behind on FreeBSD 9.0-RELEASE under KVM

Michael Sierchio kudzu at
Tue Jun 5 17:00:00 UTC 2012



On Tue, Jun 5, 2012 at 8:08 AM, Martin Dimitrov
<martin.dimitrov at> wrote:
> Hi,
> I am new to FreeBSD, decided to migrate a web server to FreeBSD. I
> recently both a VPS that claim to use KVM as a virtualization service, I
> don't know the details of the real hardware running behind nor what is
> KVM running on. Anyway I have an issue with clock on my FreeBSD
> installation that I can't live with. The clock is lagging behind, for
> example running sleep 30 is really sleeping around 35 seconds not 30.
> Also seems that NTP is not able to manage with this drift in time.
> Before posting here I red about similar problems mostly related to
> VMWare guests, but the solutions suggested are following:
> set kern.hz=100 or kern.hz=50 (doesn't work for me)
> set hint.apic.0.disabled=1 (this makes the guest hangs while booting
> also it discarding the SMP capabilities of the kernel which I assume is
> not a good idea)
> set kern.timecounter.hardware TSC (doesn't work for me)
> Is there any chance I deal with this time drifting issue somehow? If
> somebody faced such issue and managed it I would be happy to try another
> possible solution?
> Alternatively I can switch the provider with other that is using Xen for
> virtualization, I guess is better, but no guarantee that would not have
> the same issue. :(
> Cheers,
> Martin
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