From owner-freebsd-questions@FreeBSD.ORG Mon Jul 17 13:30:52 2006 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id AC16016A4E2; Mon, 17 Jul 2006 13:30:52 +0000 (UTC) (envelope-from GMcCaughan@synaptics-uk.com) Received: from mx2.synaptics-uk.com (mx2.synaptics-uk.com [194.203.111.209]) by mx1.FreeBSD.org (Postfix) with ESMTP id CDB9143D5C; Mon, 17 Jul 2006 13:30:51 +0000 (GMT) (envelope-from GMcCaughan@synaptics-uk.com) Received: from firewall.synaptics-uk.com ([194.203.111.212] helo=ukexchange2k.synaptics-inc.local) by mx2.synaptics-uk.com with esmtp (Exim 4.20) id 1G2Te0-0006Sh-PG; Mon, 17 Jul 2006 15:00:20 +0100 Received: from lists.synaptics-uk.com ([172.20.11.6]) by ukexchange2k.synaptics-inc.local with Microsoft SMTPSVC(5.0.2195.6713); Mon, 17 Jul 2006 14:30:28 +0100 Received: from [172.20.11.5] (unknown [172.20.11.5]) by lists.synaptics-uk.com (Postfix) with ESMTP id 0100B17030; Mon, 17 Jul 2006 14:10:56 +0100 (BST) From: Gareth McCaughan To: freebsd-questions@freebsd.org, freebsd-stable@freebsd.org Date: Mon, 17 Jul 2006 14:30:27 +0100 User-Agent: KMail/1.9.1 References: <200607132002.43637.gmccaughan@synaptics-uk.com> In-Reply-To: <200607132002.43637.gmccaughan@synaptics-uk.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200607171430.27752.gmccaughan@synaptics-uk.com> X-OriginalArrivalTime: 17 Jul 2006 13:30:28.0527 (UTC) FILETIME=[2B265BF0:01C6A9A5] Cc: Subject: Re: "swiN: clock sio" process taking 75% CPU 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, 17 Jul 2006 13:30:52 -0000 I wrote: > About 6 minutes after booting (on two occasions; I don't > guarantee that this doesn't vary), a process that appears > in the output of "ps" as "[swi4: clock sio]" begins to > use about 3/4 of the machine's CPU. I think it does so > more or less instantaneously. It continues to do so > indefinitely, so far as I can tell. [etc] No ideas? I'm willing to help track this down, and the machine in question is sufficiently little used that I can do so without gross inconvenience; but I don't have enough FreeBSD kernel expertise to feel like diving in blind. * A little more information, in case it's useful to anyone: | $ echo; sysctl debug | egrep to_ | debug.to_avg_mpcalls: 2890 | debug.to_avg_mtxcalls: 0 | debug.to_avg_gcalls: 768 | debug.to_avg_depth: 3815 That's with HZ = 100. Here are some numbers from a message in freebsd-ia64, from Marcel Moolenaar, in 2004-07, to someone seeing symptoms like mine. They're meant to be typical healthy numbers. Mine above look somewhat worse, but not insanely so; surely not enough to explain the difference between using 0.3% cpu and using 75%. Marcel also had HZ=100. | % sysctl debug | grep to_avg | debug.to_avg_depth: 2500 | debug.to_avg_gcalls: 1003 | debug.to_avg_mpcalls: 1255 * It would be a shame if the only conclusion to be drawn from this were "sometimes a machine running FreeBSD is just 4x slower than it should be, and no one knows why". -- g