From owner-freebsd-questions@FreeBSD.ORG Sat Jul 5 22:56:59 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 B971C1065673 for ; Sat, 5 Jul 2008 22:56:59 +0000 (UTC) (envelope-from the.real.david.allen@gmail.com) Received: from yw-out-2324.google.com (yw-out-2324.google.com [74.125.46.30]) by mx1.freebsd.org (Postfix) with ESMTP id 6D0FD8FC16 for ; Sat, 5 Jul 2008 22:56:59 +0000 (UTC) (envelope-from the.real.david.allen@gmail.com) Received: by yw-out-2324.google.com with SMTP id 9so681611ywe.13 for ; Sat, 05 Jul 2008 15:56:49 -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:in-reply-to:mime-version:content-type :content-transfer-encoding:content-disposition:references; bh=pZQBL3KEEYYuGeI5mTFUeJQP2rVRkue85VYDeZRq5z4=; b=NBvsknWjeJufBMCHQc64sObXmtoCbpJBdbxFcxKGlh3oizWnh88mYA4IOA3F6r2HjO OxsXCJwEk/+qO/noBus5xP8Lx1Yhb87xE6/Ef0U+11niXWQo1RgMoImo7At4DQBMuraq B24WKgCw+9vD4W6WHqmdEhWi8kJmpr4o2KHNI= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=LcquZljnEe51rntvt9JuidWGnXbDg7+8PuiCuO4oR0awRrn3I9JWRe1ZMNzmU2b8HT Y0c82Q6eDNSyntOtWIZSH+uAFH24OR9TpHRX7RnFqKVPNYv/kCdTP/C0cXNVodWndvKv 3PCLlLrRAkN7hvTjveQn6sgLxKaRVONvm8qAY= Received: by 10.151.50.11 with SMTP id c11mr4937850ybk.12.1215298609834; Sat, 05 Jul 2008 15:56:49 -0700 (PDT) Received: by 10.151.111.10 with HTTP; Sat, 5 Jul 2008 15:56:49 -0700 (PDT) Message-ID: <2daa8b4e0807051556t2ac2f42bgd5d2f23bf2c880d7@mail.gmail.com> Date: Sat, 5 Jul 2008 15:56:49 -0700 From: "David Allen" To: freebsd-questions@freebsd.org In-Reply-To: <54db43990806300738n33d10fe7te27b9c9f3c295a4@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> <54db43990806300738n33d10fe7te27b9c9f3c295a4@mail.gmail.com> 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: Sat, 05 Jul 2008 22:56:59 -0000 On Mon, Jun 30, 2008 at 7:38 AM, Bob Johnson wrote: > 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. I'll not worry then, but what's perplexing is that if "time going backwards" leads to confusion, why is that ntpd, as a matter of course, doesn't result in these error messages, but openntpd does? And then, why isn't anyone using openntpd getting the errors? > 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. My web searches turned a lot of noise about the above issue. Thanks for clarifying what I was reading. As for the FAQ, didn't there was one. I guess I've not needed it until now. ;-) > 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 > [...] Good to know, but this is an older single processor system (ACPI-safe). Seems I'll have to decide whether I drop openntpd and shuffle things around to other systems, or learn to live with the errors. Thanks to everyone that replied.