Date: Thu, 24 Jan 2013 08:50:02 +0200 From: Daniel Braniss <danny@cs.huji.ac.il> To: John Nielsen <lists@jnielsen.net> Cc: Adrian Chadd <adrian@freebsd.org>, freebsd-stable@freebsd.org, Ronald Klop <ronald-freebsd8@klop.yi.org> Subject: Re: time issues and ZFS Message-ID: <E1TyGdP-00031f-7E@kabab.cs.huji.ac.il> In-Reply-To: <575CDBE9-0FF3-4F93-A223-9F8FAF3FE936@jnielsen.net> 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> <575CDBE9-0FF3-4F93-A223-9F8FAF3FE936@jnielsen.net>
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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: > > > >> host: DELL PowerEdge R710, 16GB, > > 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 > set kern.eventtimer.timer=LAPIC this solved it for me. danny
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