Date: Fri, 20 Oct 2017 09:12:07 -0600 From: Ian Lepore <ian@freebsd.org> To: Boris Samorodov <bsam@passap.ru>, freebsd-current@FreeBSD.org Subject: Re: host, bhyve vm and ntpd Message-ID: <1508512327.1383.55.camel@freebsd.org> In-Reply-To: <2931f1cc-6574-b58d-4b94-5f77fa5cdb85@passap.ru> References: <2931f1cc-6574-b58d-4b94-5f77fa5cdb85@passap.ru>
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On Fri, 2017-10-20 at 14:46 +0300, Boris Samorodov wrote: > Hi All, > > I have got a host: > --- > bhyve-host% uname -a > FreeBSD sm.bsnet 12.0-CURRENT FreeBSD 12.0-CURRENT #3 r322868: Fri Aug > 25 05:25:26 MSK 2017 > bsam@builder.bsnet:/usr/obj/usr/src/sys/GENERIC-FAST amd64 amd64 > --- > > And a bhyve vm: > --- > bhyve-vm: uname -a > FreeBSD builder.bsnet 12.0-CURRENT FreeBSD 12.0-CURRENT #58 r324782: Fri > Oct 20 05:12:17 MSK 2017 > bsam@builder.bsnet:/usr/obj/usr/src/sys/PKG64X amd64 amd64 > --- > > The only difference at kernel configs is a colored console. :-) > > And here I get some weird (is it?) result at the VM (I expect ntpd to be > more stable): > --- > bhyve-vm% for t in `jot 10`; do ntpq -pn; sleep 64; done > remote refid st t when poll reach delay offset > jitter > ============================================================================== > XX.XX.XX.1 XX.XX.XX.245 4 u 9 64 3 0.605 -1.202 > 316.407 > XX.XX.XX.1 XX.XX.XX.245 4 u 7 64 7 0.605 -1.202 > 358.395 > *XX.XX.XX.1 XX.XX.XX.245 4 u 5 64 17 0.615 -328.42 > 181.405 > *XX.XX.XX.1 XX.XX.XX.245 4 u 3 64 37 0.615 -328.42 > 214.868 > *XX.XX.XX.1 XX.XX.XX.245 4 u 67 64 37 0.615 -328.42 > 214.868 > *XX.XX.XX.1 XX.XX.XX.245 4 u 63 64 77 0.615 -328.42 > 268.618 > *XX.XX.XX.1 XX.XX.XX.245 4 u 60 64 177 0.615 -328.42 > 333.175 > XX.XX.XX.1 .STEP. 16 u 1910 64 0 0.000 0.000 > 0.000 > XX.XX.XX.1 XX.XX.XX.245 4 u 27 64 1 0.703 -262.63 > 0.004 > XX.XX.XX.1 XX.XX.XX.245 4 u 31 64 1 0.649 -331.43 > 68.800 > --- > > At the same time host's results are very stable: > --- > bhyve-host% for t in `jot 10`; do ntpq -pn; sleep 64; done > remote refid st t when poll reach delay offset > jitter > ============================================================================== > > > > *XX.XX.XX.1 XX.XX.XX.245 4 u 1 64 1 0.401 0.176 > 0.106 > *XX.XX.XX.1 XX.XX.XX.245 4 u 6 64 3 0.401 0.176 > 0.459 > *XX.XX.XX.1 XX.XX.XX.245 4 u 3 64 7 0.401 0.176 > 0.940 > *XX.XX.XX.1 XX.XX.XX.245 4 u 67 64 7 0.401 0.176 > 0.940 > *XX.XX.XX.1 XX.XX.XX.245 4 u 64 64 17 0.401 0.176 > 1.566 > *XX.XX.XX.1 XX.XX.XX.245 4 u 60 64 37 0.448 1.275 > 1.739 > *XX.XX.XX.1 XX.XX.XX.245 4 u 55 64 77 0.448 1.275 > 2.365 > *XX.XX.XX.1 XX.XX.XX.245 4 u 53 64 177 0.448 1.275 > 3.110 > *XX.XX.XX.1 XX.XX.XX.245 4 u 50 64 377 0.448 1.275 > 3.929 > *XX.XX.XX.1 XX.XX.XX.245 4 u 45 64 377 0.443 8.750 > 4.722 > --- > > The network is organized via bridge -- host igb and vm tap interfaces > are members of one bridge. > > Are those results expected? Does it smell like a bug? Should I dig > furter? > So it is repeatedly stepping the clock in the VM? (Set kern.timecounter.stepwarnings=1 to log steps). That is usually a sign that the chosen timecounter is running at a different frequency than it claimed to be when it registered itself -- the host may not be emulating the timer hardware properly in the guest. What is the output of sysctl kern.timecounter in the vm? Also, what is the output of ntptime(8) in the vm? -- Ian
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