Hi,

On Fri, Apr 10, 2015 at 3:47 PM, Matthew Grooms <mgro...@shrew.net> wrote:
> Perhaps applying this commit would have some positive effect ( HPET vs LAPIC
> )?
>
> https://docs.freebsd.org/cgi/getmsg.cgi?fetch=885358+0+archive/2015/svn-src-head/20150322.svn-src-head
>

No, it's an orthogonal change.

The change above only causes the APIC to be preferred as an event
timer (i.e. nothing to do with the choice of timecounter).

best
Neel

> -Matthew
>
>
> On 4/10/2015 12:51 PM, Stephen Stuart wrote:
>>
>> I think the right thing is to set (in /boot/loader.conf)
>> kern.timecounter.tc.TSC-low.quality to a value higher than that for HPET,
>> to force the clock choice over what the kernel decides for the hardware
>> that you're running on. See timecounters(4).
>>
>> Stephen
>>
>> On Fri, Apr 10, 2015 at 10:35 AM, Paul Vixie <p...@redbarn.org> wrote:
>>
>>> here is a representative one-hour sample of ntp messages from
>>> /var/log/messages on a freebsd 10.1 bhyve guest:
>>>
>>>> Apr 10 12:00:46 family ntpd[634]: time reset -0.613057 s
>>>> Apr 10 12:17:02 family ntpd[634]: time reset -0.604933 s
>>>> Apr 10 12:33:51 family ntpd[634]: time reset -0.650622 s
>>>> Apr 10 12:55:06 family ntpd[634]: time reset -0.743930 s
>>>
>>>
>>> that's with kern.timecounter.hardware: HPET, which is the default.
>>>
>>> a "time reset" from ntpd means the clock either won't slew at all or
>>> can't slew fast enough. in other words a normal freebsd 10.1 server can
>>> run for months or even years without ever outputting one of these
>>> messages.
>>>
>>> google reports that some folks have had good luck with
>>> kern.timecounter.hardware: TSC-low. so i tried that on another freebsd
>>> 10.1 bhyve guest on the same bhyve server, with dramatic results -- no
>>> more ntpd messages.
>>>
>>> can we make TSC-low the default?
>>>
>>> vixie
>>>
>>>
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>
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