Date: Mon, 21 Jan 2013 08:54:27 -0700 From: Ian Lepore <ian@FreeBSD.org> To: Daniel Braniss <danny@cs.huji.ac.il> Cc: freebsd-stable@FreeBSD.org, Ronald Klop <ronald-freebsd8@klop.yi.org> Subject: Re: time issues and ZFS Message-ID: <1358783667.32417.434.camel@revolution.hippie.lan> In-Reply-To: <E1TxJP2-000DS8-DJ@kabab.cs.huji.ac.il> References: <E1TxFcr-0006dx-MX@kabab.cs.huji.ac.il> <1358780588.32417.414.camel@revolution.hippie.lan> <E1TxJP2-000DS8-DJ@kabab.cs.huji.ac.il>
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On Mon, 2013-01-21 at 17:35 +0200, Daniel Braniss wrote: > ... > > > > What's the output of sysctl kern.eventtimer? > > kern.eventtimer.periodic is 0 > > > Does the bad behavior > > change if you set kern.eventimer.periodic=1? > > > > setting kern.eventtimer.timer=LAPIC > instead of the default HPET made the missing cpu timers to appear: > # vmstat -i > interrupt total rate > irq3: uart1 1695 0 > irq4: uart0 5 0 > irq19: ehci0 3875 0 > irq20: hpet0 uhci3 5495755 1135 > irq21: uhci2 ehci1 29 0 > irq23: atapci0 48 0 > cpu0:timer 7063 1 > irq256: bce0 117073 24 > irq260: mfi0 51083 10 > irq261: mfi1 3088 0 > cpu1:timer 484 0 > cpu14:timer 36 0 > cpu6:timer 486 0 > cpu8:timer 38 0 > cpu5:timer 38 0 > cpu15:timer 38 0 > cpu7:timer 32 0 > cpu12:timer 38 0 > cpu3:timer 40 0 > cpu9:timer 36 0 > cpu10:timer 34 0 > cpu11:timer 37 0 > cpu2:timer 33 0 > cpu13:timer 40 0 > cpu4:timer 36 0 > Total 5681160 1173 > > is this relevant? I'll have to let someone who knows modern x86 hardware better comment on the relative merits of hpet vs. lapic timers. If it was using hpet in one-shot mode, and changing it to hpet in periodic mode makes the problem go away, that might be a clue that there's something wrong in the hpet eventtimer start or interrupt routines. I wonder if a single missed interrupt in one-shot mode would bring an eventtimer to a halt like that? And if so, then what is it about manually asking for the date that kicks it into running again? -- Ian
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