From owner-freebsd-current@FreeBSD.ORG Sat Jan 31 22:52:53 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 AF0B916A4CE; Sat, 31 Jan 2004 22:52:53 -0800 (PST) Received: from mailout1.pacific.net.au (mailout1.pacific.net.au [61.8.0.84]) by mx1.FreeBSD.org (Postfix) with ESMTP id E1F0943D2D; Sat, 31 Jan 2004 22:52:51 -0800 (PST) (envelope-from bde@zeta.org.au) Received: from mailproxy1.pacific.net.au (mailproxy1.pacific.net.au [61.8.0.86])i116qpLE005392; Sun, 1 Feb 2004 17:52:51 +1100 Received: from gamplex.bde.org (katana.zip.com.au [61.8.7.246]) i116qnt4025357; Sun, 1 Feb 2004 17:52:49 +1100 Date: Sun, 1 Feb 2004 17:52:48 +1100 (EST) From: Bruce Evans X-X-Sender: bde@gamplex.bde.org To: Don Lewis In-Reply-To: <200402010119.i111J67E096098@gw.catspoiler.org> Message-ID: <20040201172521.X7622@gamplex.bde.org> References: <200402010119.i111J67E096098@gw.catspoiler.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: hlen@ig.com.br cc: freebsd-current@freebsd.org Subject: Re: Syncer "giving up" on buffers 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: Sun, 01 Feb 2004 06:52:53 -0000 On Sat, 31 Jan 2004, Don Lewis wrote: > On 31 Jan, Herculano de Lima Einloft Neto wrote: [Someone wrote] > >>> Waiting (max 60 seconds) for system process `vnlru' to stop...stopped > >>> Waiting (max 60 seconds) for system process `bufdaemon' to stop...stopped > >>> Waiting (max 60 seconds) for system process `syncer' to stop...stopped > >>> > >>> syncing disks, buffers remaining... 8 8 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 > >>> giving up on 6 buffers > I've also seen this happen if I run the following sequence of commands: > make installworld > mergemaster > shutdown -r now > and don't wait long enough between mergemaster and shutdown. My > suspicion is that the syncer is being shut before all the soft update > dependencies have been resolved, and the unresolved dependencies are > preventing some buffers from being written. I think mergmaster is > triggering the problem because it deletes a large directory tree just > before it exits. Waiting a little while to shutdown works around the > problem by giving the syncer time to clean things up. I saw this for a similar operation: tar ... to copy most of /usr/src to a new file system with soft-updates rm -rf /new/filesystem/* reboot using reboot(8) with no args (or maybe ctrl-alt-del) BTW, copying /usr/src (or perhaps a slightly larger or smaller tree, depending on the memory size or buffer cache size) shows other badness in soft updates' buffering. bufdaemon sometimes consumes almost 100% of the CPU for a significant fraction of the copying time. This makes the copy go 2-3 times slower than it used to in favourable conditions (source cached and target new). My benchmarks show that this broke sometime between 2002/06/05 and 2003/09/23. Bruce