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Date:      Fri, 10 Apr 2015 14:07:23 -0400
From:      Allan Jude <allanjude@freebsd.org>
To:        freebsd-virtualization@freebsd.org
Subject:   Re: bhyve clock problem, solved by kern.timecounter.hardware="TSC-low" in /etc/sysctl.conf
Message-ID:  <5528115B.7060509@freebsd.org>
In-Reply-To: <552810CE.7020502@redbarn.org>
References:  <552809F4.6070206@redbarn.org> <CAOb7DXGAWiTUvmq5xJT8Z8W9D3hFuWeHQ-vbADw2AP0Fv4e8Lw@mail.gmail.com> <552810CE.7020502@redbarn.org>

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On 2015-04-10 14:05, Paul Vixie wrote:
>=20
>=20
> 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).
>=20
> if every bhyve guest ever is going to need this, then the interface
> offered to the guest kernel ought to present the right set of defaults
> to cause the right choice to be made, or the guest kernel must simply
> "know better". in other words me adding something to /boot/loader.conf
> or /etc/sysctl.conf in every single bhyve guest ever is an indication
> that we're doing something wrong elsewhere.
>=20

I think that was the suggestion, to change the login in timecounter(4)
to detect bhyve (or all virtualization?) and change the quality values
for the different times, so that the best one for the environment
(virtualized, rather than physical) is selected automatically.

Temporarily, as a workaround, /boot/loader.conf is better because it is
applied sooner than /etc/sysctl.conf

--=20
Allan Jude


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