From owner-freebsd-stable@FreeBSD.ORG Mon Jan 21 15:54:51 2013 Return-Path: Delivered-To: freebsd-stable@FreeBSD.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 49F3798 for ; Mon, 21 Jan 2013 15:54:51 +0000 (UTC) (envelope-from ian@FreeBSD.org) Received: from duck.symmetricom.us (duck.symmetricom.us [206.168.13.214]) by mx1.freebsd.org (Postfix) with ESMTP id CCCC8AFA for ; Mon, 21 Jan 2013 15:54:50 +0000 (UTC) Received: from damnhippie.dyndns.org (daffy.symmetricom.us [206.168.13.218]) by duck.symmetricom.us (8.14.6/8.14.6) with ESMTP id r0LFsobG013381 for ; Mon, 21 Jan 2013 08:54:50 -0700 (MST) (envelope-from ian@FreeBSD.org) Received: from [172.22.42.240] (revolution.hippie.lan [172.22.42.240]) by damnhippie.dyndns.org (8.14.3/8.14.3) with ESMTP id r0LFsRPW011812; Mon, 21 Jan 2013 08:54:27 -0700 (MST) (envelope-from ian@FreeBSD.org) Subject: Re: time issues and ZFS From: Ian Lepore To: Daniel Braniss In-Reply-To: References: <1358780588.32417.414.camel@revolution.hippie.lan> Content-Type: text/plain; charset="us-ascii" Date: Mon, 21 Jan 2013 08:54:27 -0700 Message-ID: <1358783667.32417.434.camel@revolution.hippie.lan> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 FreeBSD GNOME Team Port Content-Transfer-Encoding: 7bit Cc: freebsd-stable@FreeBSD.org, Ronald Klop X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 21 Jan 2013 15:54:51 -0000 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