From owner-freebsd-stable@FreeBSD.ORG Thu Dec 15 21:04:23 2011 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 42FF91065675 for ; Thu, 15 Dec 2011 21:04:23 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from QMTA11.westchester.pa.mail.comcast.net (qmta11.westchester.pa.mail.comcast.net [76.96.59.211]) by mx1.freebsd.org (Postfix) with ESMTP id 060E88FC08 for ; Thu, 15 Dec 2011 21:04:22 +0000 (UTC) Received: from omta10.westchester.pa.mail.comcast.net ([76.96.62.28]) by QMTA11.westchester.pa.mail.comcast.net with comcast id 9YtR1i0040cZkys5BZ4P1r; Thu, 15 Dec 2011 21:04:23 +0000 Received: from koitsu.dyndns.org ([67.180.84.87]) by omta10.westchester.pa.mail.comcast.net with comcast id 9Z4N1i00e1t3BNj3WZ4NLD; Thu, 15 Dec 2011 21:04:23 +0000 Received: by icarus.home.lan (Postfix, from userid 1000) id 38D30102C19; Thu, 15 Dec 2011 13:04:21 -0800 (PST) Date: Thu, 15 Dec 2011 13:04:21 -0800 From: Jeremy Chadwick To: Doug Barton Message-ID: <20111215210421.GA33083@icarus.home.lan> References: <4EEA5DD0.1040009@FreeBSD.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4EEA5DD0.1040009@FreeBSD.org> User-Agent: Mutt/1.5.21 (2010-09-15) Cc: freebsd-stable@FreeBSD.org Subject: Re: swi4: clock taking 40% cpu?!? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 Dec 2011 21:04:23 -0000 On Thu, Dec 15, 2011 at 12:51:28PM -0800, Doug Barton wrote: > Howdy, > > Web server under heavy'ish load (7 on a 2 cpu system) running > 8.2-RELEASE-p4 i386 I'm seeing this: > > PID USERNAME PRI NICE SIZE RES STATE C TIME WCPU COMMAND > 12 root -32 - 0K 112K WAIT 0 129:01 39.99% {swi4: clock} > > Any ideas why the clock should be taking so much cpu? HZ=100 if that > makes a difference ... Could be wrong, but I believe this correlates with IRQ 4. What does vmstat -i show for a total and rate for irq4 if you run it, wait a few seconds, then run it again? Does the number greatly/rapidly increase? Shot in the dark here, but the only thing I can think of that might cause this is software being extremely aggressive with calls to things like gettimeofday(2) or clock_gettime(2). Really not sure. ntpd maybe (unlikely but possible)? Sort of grasping at straws here. -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, US | | Making life hard for others since 1977. PGP 4BD6C0CB |