From owner-freebsd-questions@FreeBSD.ORG Mon Jun 30 14:38:27 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0A4951065670 for ; Mon, 30 Jun 2008 14:38:27 +0000 (UTC) (envelope-from fbsdlists@gmail.com) Received: from rv-out-0506.google.com (rv-out-0506.google.com [209.85.198.230]) by mx1.freebsd.org (Postfix) with ESMTP id D130E8FC0C for ; Mon, 30 Jun 2008 14:38:26 +0000 (UTC) (envelope-from fbsdlists@gmail.com) Received: by rv-out-0506.google.com with SMTP id b25so1586552rvf.43 for ; Mon, 30 Jun 2008 07:38:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:cc:in-reply-to:mime-version:content-type :content-transfer-encoding:content-disposition:references; bh=Vy9C+3uKOcHOOgAhoRv+S05t48KONFHsVPlv2GcOq0Q=; b=ib97/M7MOrVrAEgmIMW/26GS1XPqsmKOJEeRSd7ecJ5JEVMeHujXbc8W02wtsiv805 wda952uucNquQ2ni5eiDgmt/DfH0/t/n7T7CfNDJoospzpZIA1GRdnNT97mdsmBeFhi1 yI/r7/V5Ke95w2/FKJFaIo/zDJZoY+dj9uLBE= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=jzHAbeA5SUkfjLywc45bEonuhS5Wf0H0JULhavkhpHUrUTUKX+wEGfw/N7loLJIlOh CNS6UCoRW7I9/AgNwFbQWM6jmNQ2XkxTB8OCV+OD0wA50y1F/FNDkWtzptGOjqeqGMn8 s2qe5rxB7+/qpT/YgtauTY0fGoWpSzLXAZApg= Received: by 10.141.169.11 with SMTP id w11mr2697795rvo.76.1214836706569; Mon, 30 Jun 2008 07:38:26 -0700 (PDT) Received: by 10.141.175.4 with HTTP; Mon, 30 Jun 2008 07:38:26 -0700 (PDT) Message-ID: <54db43990806300738n33d10fe7te27b9c9f3c295a4@mail.gmail.com> Date: Mon, 30 Jun 2008 10:38:26 -0400 From: "Bob Johnson" To: "David Allen" In-Reply-To: <2daa8b4e0806300627s39d49347r9e0e5675e4c25088@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <2daa8b4e0806300627s39d49347r9e0e5675e4c25088@mail.gmail.com> Cc: freebsd-questions@freebsd.org Subject: Re: calcru: runtime went backwards errors X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 30 Jun 2008 14:38:27 -0000 On 6/30/08, David Allen wrote: > I've been seeing errors like the following appearing: > > Jun 30 03:13:57 ford kernel: calcru: runtime went backwards from 261 > usec to 258 usec for pid 516 (devd) [...] > Jun 30 03:13:57 ford kernel: calcru: runtime went backwards from 486 > usec to 481 usec for pid 0 (swapper) > > and narrowed down the cause to openntpd. > > Do these errors fall into the Mostly Harmless category? It's probably just an annoyance, unless it is happening so often it causes other problems. The FreeBSD FAQ used to have a nice explanation of this, but it has been replaced by a discussion that simply assumes the problem is caused by the Intel SpeedStep implementation on your motherboard: http://www.freebsd.org/doc/en_US.ISO8859-1/books/faq/troubleshoot.html#Q5.24. But in general, this error can be caused by several things, including a device that is slow to respond to interrupts. One thing that often helps on SMP systems is to make sure your timecounter isn't using TSC: $ sysctl kern.timecounter kern.timecounter.tick: 1 kern.timecounter.choice: TSC(-100) HPET(900) ACPI-fast(1000) i8254(0) dummy(-1000000) kern.timecounter.hardware: ACPI-fast [...] - Bob