Date: Thu, 11 Oct 2012 01:43:03 +0300 From: Alexander Motin <mav@FreeBSD.org> To: freebsd-stable@FreeBSD.org, jmg@funkthat.com Subject: Re: time keeps on slipping... slipping... Message-ID: <5075F9F7.1040007@FreeBSD.org> In-Reply-To: <20121008040239.GE1967@funkthat.com> References: <20121008040239.GE1967@funkthat.com>
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On 08.10.2012 07:02, John-Mark Gurney wrote: > I recently put together a new machine w/ a SuperMicro H8SCM and an > AMD Opteron 4228 HE... I've having an issue where the clock on the > machine skips around... The wierd part is that it's very sudden when > it happens... ntp sometimes brings it back, but it can't when the clock > gets too far ahread (1000 seconds), ntp dies... > > In order to catch it happening, I ran a sleep 60 loop fetching time > from another server that keeps time correctly via: > while sleep 60; do echo -n h2:; nc h2 13; date; ntpdate h2.funkthat.com; done > > here are some snippits: > h2:Sun Oct 7 17:12:54 2012^M > Sun Oct 7 17:12:54 PDT 2012 > 7 Oct 17:12:54 ntpdate[31036]: the NTP socket is in use, exiting > h2:Sun Oct 7 17:13:48 2012^M > Sun Oct 7 17:20:21 PDT 2012 > 7 Oct 17:20:21 ntpdate[31045]: the NTP socket is in use, exiting > > but then ntp brings it back in sync: > h2:Sun Oct 7 17:28:49 2012^M > Sun Oct 7 17:35:21 PDT 2012 > 7 Oct 17:35:21 ntpdate[31164]: the NTP socket is in use, exiting > h2:Sun Oct 7 17:29:49 2012^M > Sun Oct 7 17:29:49 PDT 2012 > 7 Oct 17:29:49 ntpdate[31170]: the NTP socket is in use, exiting > > It happens pretty often: > Oct 7 00:19:13 gold ntpd[3721]: time reset -785.347912 s > Oct 7 00:46:37 gold ntpd[3721]: time reset -392.673256 s > Oct 7 01:04:24 gold ntpd[3721]: time reset -785.346533 s > Oct 7 15:00:59 gold ntpd[3721]: time reset -392.681720 s > Oct 7 16:32:11 gold ntpd[3721]: time reset -392.671268 s > Oct 7 17:29:29 gold ntpd[3721]: time reset -392.671752 s > Oct 7 18:04:37 gold ntpd[3721]: time reset -785.346987 s > > but as you can see above, the time slip happens abruptly.. looks like > a rounding error or something... > > I'm now reducing the sleep to 5 seconds... but as you can see the sleep > ends a few seconds early and local time suddenly jumped forward 6 > minutes 33 seconds... > > $ sysctl kern.timecounter > kern.timecounter.fast_gettime: 1 > kern.timecounter.tick: 1 > kern.timecounter.choice: TSC-low(1000) ACPI-safe(850) HPET(950) i8254(0) dummy(-1000000) > kern.timecounter.hardware: TSC-low > kern.timecounter.stepwarnings: 0 > kern.timecounter.tc.i8254.mask: 65535 > kern.timecounter.tc.i8254.counter: 11598 > kern.timecounter.tc.i8254.frequency: 1193182 > kern.timecounter.tc.i8254.quality: 0 > kern.timecounter.tc.HPET.mask: 4294967295 > kern.timecounter.tc.HPET.counter: 3257069245 > kern.timecounter.tc.HPET.frequency: 14318180 > kern.timecounter.tc.HPET.quality: 950 > kern.timecounter.tc.ACPI-safe.mask: 16777215 > kern.timecounter.tc.ACPI-safe.counter: 4219134510 > kern.timecounter.tc.ACPI-safe.frequency: 3579545 > kern.timecounter.tc.ACPI-safe.quality: 850 > kern.timecounter.tc.TSC-low.mask: 4294967295 > kern.timecounter.tc.TSC-low.counter: 2854866610 > kern.timecounter.tc.TSC-low.frequency: 10937740 > kern.timecounter.tc.TSC-low.quality: 1000 > kern.timecounter.smp_tsc: 1 > kern.timecounter.invariant_tsc: 1 > $ sysctl kern.eventtimer > kern.eventtimer.choice: LAPIC(400) i8254(100) RTC(0) > kern.eventtimer.et.LAPIC.flags: 15 > kern.eventtimer.et.LAPIC.frequency: 100002217 > kern.eventtimer.et.LAPIC.quality: 400 > kern.eventtimer.et.i8254.flags: 1 > kern.eventtimer.et.i8254.frequency: 1193182 > kern.eventtimer.et.i8254.quality: 100 > kern.eventtimer.et.RTC.flags: 17 > kern.eventtimer.et.RTC.frequency: 32768 > kern.eventtimer.et.RTC.quality: 0 > kern.eventtimer.periodic: 0 > kern.eventtimer.timer: LAPIC > kern.eventtimer.activetick: 1 > kern.eventtimer.idletick: 0 > kern.eventtimer.singlemul: 2 > > I have switched my timecounter to HPET to see if things are different... > > Any clues? Mentioned switching to HPET could tell a lot about the problem. Switching event timer also may be interesting. -- Alexander Motin
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