Re: host, bhyve vm and ntpd

From: Boris Samorodov <bsam_at_passap.ru>
Date: Sun, 22 Oct 2017 19:16:41 +0300
22.10.2017 19:02, Ian Lepore ÐÉÛÅÔ:
> On Sun, 2017-10-22 at 11:31 +0300, Boris Samorodov wrote:
>> 22.10.2017 01:15, Ian Lepore ÐÉÛÅÔ:
>>>
>>> On Sat, 2017-10-21 at 17:07 -0400, Michael Voorhis wrote:
>>>>
>>>> Ian Lepore writes:
>>>>>
>>>>>
>>>>> Beyond that, I'm not sure what else to try. šIt might be necessary to
>>>>> get some bhyve developers involved (I know almost nothing about it).
>>>> NTPD behaves more normally on uniprocessor VMs.
>>>>
>>>> A FreeBSD bhyve-guest running on a freebsd host will select a
>>>> different timecounter depending on whether it is a multiprocessor or a
>>>> uniprocessor.ššMy uniprocessor bhyve-vm selected TSC-low as the best
>>>> timecounter in a uniprocessor.ššNTP functions there as expected.
>>>>
>>>> kern.timecounter.choice: TSC-low(1000) ACPI-fast(900) HPET(950) i8254(0) dummy(-1000000)
>>>> kern.timecounter.hardware: TSC-low
>>>>
>>>> The very same VM, when given two total CPUs, selected HPET (if I
>>>> recall) and the timekeeping with NTPD was unreliable, with many
>>>> step-resets to the clock.
>>>>
>>> Hmm, I just had glance at the code inšsys/amd64/vmm/io/vhpet.c and it
>>> looks right. šI wonder if this is just a simple roundoff error in
>>> converting between 10.0MHz and SBT units? šIf so, that could be wished
>>> away easily by using a power-of-2 frequency for the virtual HPET. šI
>>> wonder if the attached patch is all that's needed?
>> I've tried the patch (at bhyve guest) and nothing has changed. Should
>> the patched system be tested at bhyve guest or bhyve host?
>>
> 
> Oh, I'm sorry, I should have mentioned that's for the host side.

NP, that's OK.

However, the host is busy now, and I'll have an opportunity to test host
only tomorrow evening.

Ian, thank you for your help!

-- 
WBR, bsam
Received on Sun Oct 22 2017 - 14:16:46 UTC

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