Date: Wed, 23 Jan 2013 16:11:57 -0700 From: John Nielsen <lists@jnielsen.net> To: Adrian Chadd <adrian@freebsd.org> Cc: freebsd-stable@freebsd.org, Ronald Klop <ronald-freebsd8@klop.yi.org> Subject: Re: time issues and ZFS Message-ID: <575CDBE9-0FF3-4F93-A223-9F8FAF3FE936@jnielsen.net> In-Reply-To: <CAJ-VmomdQORjs55ooW55Rgg0i1M13PPtnmCPRrp__btEWQz=4g@mail.gmail.com> References: <E1TxFcr-0006dx-MX@kabab.cs.huji.ac.il> <1358780588.32417.414.camel@revolution.hippie.lan> <E1TxJP2-000DS8-DJ@kabab.cs.huji.ac.il> <1358783667.32417.434.camel@revolution.hippie.lan> <CAJ-Vmo=2Dmf4Lb-uoUQDrybyRSS=_bnV5KcNYGg5MnMxfhhu7w@mail.gmail.com> <E1TxYHa-0002yo-4Y@kabab.cs.huji.ac.il> <CAJ-VmomdQORjs55ooW55Rgg0i1M13PPtnmCPRrp__btEWQz=4g@mail.gmail.com>
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On Jan 22, 2013, at 2:40 AM, Adrian Chadd <adrian@freebsd.org> wrote: > On Jan 21, 2013, at 4:33 AM, Daniel Braniss <danny@cs.huji.ac.il> = wrote: >=20 >> host: DELL PowerEdge R710, 16GB,=20 I administer a Dell PowerEdge R710 and I've been seeing the exact same = thing. It's currently running FreeBSD 9.0-STABLE #0 r236355. It has a = ZFS pool which sees moderate load most of the time but can be very high = at times (when certain scripts run, etc.). I hadn't previously = correlated the issue with ZFS load but that is very possible. I set a cron job to restart ntpd when it dies (because the time = difference exceeds the sanity check). The cron job runs "every 20 = minutes", but that varies greatly when the system stops counting. The = time offset from ntpdate (which the script runs before restarting ntpd) = varies a lot, but always in increments of 300 seconds. I've seen = everything from 1200 to 23100. (Yes, that's 23 thousand seconds aka 6 = hours 25 minutes that the system wasn't keeping time for.) Sysctl kern.timecounter.hardware defaults to HPET. I experimented with = setting it to ACPI-fast but the issue persisted so I put it back. kern.timecounter.choice: TSC-low(-100) ACPI-fast(900) HPET(950) i8254(0) = dummy(-1000000) I first installed the box with an older 9.0-STABLE and this issue was = not present. I have been tracking -STABLE on it (albeit irregularly) so = I'm not sure when the issue came up. > Have you run tests with the machdep.idle value changed, and fiddling > kern.eventtimer.periodic / kern.eventtimer.idletick ? I would love to resolve this and am able to do some experimenting. I've = _usually_ been seeing the issue 2-3 times every 1-2 days, but I did just = make some changes: disabling ZFS compression and deduplication on all pools updated to 9.1-STABLE from yesterday (r245821) If the issue persists I will try changing some of the sysctls above and = follow up with the result. If it goes away, I'll try to remember to = report that too. JN
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