From owner-freebsd-current@FreeBSD.ORG Fri Jan 30 11:18:31 2004 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 81C2716A4CE for ; Fri, 30 Jan 2004 11:18:31 -0800 (PST) Received: from mail3.speakeasy.net (mail3.speakeasy.net [216.254.0.203]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3420F43D41 for ; Fri, 30 Jan 2004 11:18:23 -0800 (PST) (envelope-from jhb@FreeBSD.org) Received: (qmail 17312 invoked from network); 30 Jan 2004 19:18:22 -0000 Received: from dsl027-160-063.atl1.dsl.speakeasy.net (HELO server.baldwin.cx) ([216.27.160.63]) (envelope-sender ) encrypted SMTP for ; 30 Jan 2004 19:18:22 -0000 Received: from 10.50.40.205 (gw1.twc.weather.com [216.133.140.1]) by server.baldwin.cx (8.12.10/8.12.10) with ESMTP id i0UJICM4076005; Fri, 30 Jan 2004 14:18:18 -0500 (EST) (envelope-from jhb@FreeBSD.org) From: John Baldwin To: Bruce Evans , Kris Kennaway Date: Fri, 30 Jan 2004 13:14:46 -0500 User-Agent: KMail/1.5.4 References: <200401292134.i0TLYSfD019841@Espresso.NEEBU.Net> <20040129231521.GA68516@xor.obsecurity.org> <20040131030718.I602@gamplex.bde.org> In-Reply-To: <20040131030718.I602@gamplex.bde.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200401301314.46146.jhb@FreeBSD.org> X-Spam-Checker-Version: SpamAssassin 2.55 (1.174.2.19-2003-05-19-exp) cc: current@freebsd.org Subject: Re: unusually high load averages X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 30 Jan 2004 19:18:31 -0000 On Friday 30 January 2004 12:03 pm, Bruce Evans wrote: > On Thu, 29 Jan 2004, Kris Kennaway wrote: > > On Fri, Jan 30, 2004 at 12:08:17AM +0100, Melvyn Sopacua wrote: > > > On Thursday 29 January 2004 22:34, Jake Khuon wrote: > > > > I'm noticing some unusually high load averages even though nothing > > > > seems to be taking up much CPU. This started happening with a recent > > > > cvsup (last night). Anyone know what might be causing this? > > > > > > You are actually seeing > 0.00% CPU/WCPU, cause with me everything is > > > zero, allthough I know for sure that's not true. > > > > You both forgot to mention which scheduler you're using. This is > > important. > > It's easy enough to list the bugs for each scheduler and to determine the > scheduler (and the approximate kernel source version) by observing the > bugs: > > 0.00% CPU/WCPU: > This indicates a 4BSD scheduler with the bug that I fixed recently. The > bug lived for almost a month. > > CPU always the same as WCPU: > This indicates a ULE scheduler and certain bugs. ULE doesn't maintain > all the statistics related to the old scheduler or provide alternatives > (it just fakes some), and statistics programs blindly display all the > old statistics. > > High load average despite only idle processes running: > This seems to be scheduler-independent. Running top to watch the load > average raises the load average by about 0.1. I think the problem is > that loadav() is now a kthread that restarted by a timeout, so it now > sees a herd of other processes that are restarted by the same timeout. > Previously it was run as a timeout and other threads were put on the > run queue by a timeout; the ordering of the timeouts was hopefully > random so that loadav() saw the correct number of processes restarted > by timeouts, on average. Now loadav() sees all lower priority processes > that are restarted by the same timeout (since they are all restarted but > loadav() runs first). If loadav is truly unimportant, we could give it a fairly low priority so other processes ran first. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org