Date: Fri, 10 Apr 2015 21:27:18 -0700 From: Neel Natu <neelnatu@gmail.com> To: Matthew Grooms <mgrooms@shrew.net> Cc: "freebsd-virtualization@freebsd.org" <freebsd-virtualization@freebsd.org> Subject: Re: bhyve clock problem, solved by kern.timecounter.hardware="TSC-low" in /etc/sysctl.conf Message-ID: <CAFgRE9GVvNYwJ4xknj7c%2BuFAykRaoYR3-vu5eYFmf27ZwqvONA@mail.gmail.com> In-Reply-To: <552852FB.1060901@shrew.net> References: <552809F4.6070206@redbarn.org> <CAOb7DXGAWiTUvmq5xJT8Z8W9D3hFuWeHQ-vbADw2AP0Fv4e8Lw@mail.gmail.com> <552852FB.1060901@shrew.net>
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Hi, On Fri, Apr 10, 2015 at 3:47 PM, Matthew Grooms <mgrooms@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 <paul@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 >>> >>> >>> _______________________________________________ >>> freebsd-virtualization@freebsd.org mailing list >>> http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization >>> To unsubscribe, send any mail to " >>> freebsd-virtualization-unsubscribe@freebsd.org" >>> >> _______________________________________________ >> freebsd-virtualization@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization >> To unsubscribe, send any mail to >> "freebsd-virtualization-unsubscribe@freebsd.org" > > > _______________________________________________ > freebsd-virtualization@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization > To unsubscribe, send any mail to > "freebsd-virtualization-unsubscribe@freebsd.org"
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