From owner-freebsd-stable@FreeBSD.ORG Wed Jan 16 21:29:00 2008 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 18DB316A46C for ; Wed, 16 Jan 2008 21:29:00 +0000 (UTC) (envelope-from mcdouga9@egr.msu.edu) Received: from mx.egr.msu.edu (surfnturf.egr.msu.edu [35.9.37.164]) by mx1.freebsd.org (Postfix) with ESMTP id A724713C461 for ; Wed, 16 Jan 2008 21:28:57 +0000 (UTC) (envelope-from mcdouga9@egr.msu.edu) Received: from localhost (localhost.egr.msu.edu [127.0.0.1]) by mx.egr.msu.edu (Postfix) with ESMTP id 230F62EB96D for ; Wed, 16 Jan 2008 16:13:32 -0500 (EST) X-Virus-Scanned: amavisd-new at egr.msu.edu Received: from mx.egr.msu.edu ([127.0.0.1]) by localhost (surfnturf.egr.msu.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id DHDmnKXXoJtj for ; Wed, 16 Jan 2008 16:13:32 -0500 (EST) Received: from localhost (daemon.egr.msu.edu [35.9.44.65]) by mx.egr.msu.edu (Postfix) with ESMTP id EF49F2EB927 for ; Wed, 16 Jan 2008 16:13:31 -0500 (EST) Received: by localhost (Postfix, from userid 21281) id D95C833C3D; Wed, 16 Jan 2008 16:13:31 -0500 (EST) Date: Wed, 16 Jan 2008 16:13:31 -0500 From: Adam McDougall To: freebsd-stable@freebsd.org Message-ID: <20080116211331.GL23094@egr.msu.edu> References: <20071203054207.GA1153@aleph.niw.com.au> <4787AAF4.1020905@FreeBSD.org> <20080112033147.GX60060@server.vk2pj.dyndns.org> <200801120005.38972.jhb@freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200801120005.38972.jhb@freebsd.org> User-Agent: Mutt/1.5.17 (2007-11-01) Subject: Re: Swapping caused by very large (regular) file size 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: Wed, 16 Jan 2008 21:29:00 -0000 On Sat, Jan 12, 2008 at 12:05:38AM -0500, John Baldwin wrote: On Friday 11 January 2008 10:31:47 pm Peter Jeremy wrote: > On Fri, Jan 11, 2008 at 06:44:20PM +0100, Kris Kennaway wrote: > >Ian West wrote: > >> dd if=/dev/zero bs=32768 of=junkfile count=100000 seems to do it quite > >> reliably on all the boxes I have tested ? > > > >I am unable to reproduce this on 7.0. > > I can't reproduce it on 6.3-PRERELEASE/amd64 with 1GB RAM. > > vmstat -s;dd if=/dev/zero bs=32768 of=junkfile count=100000;vmstat -s > shows the following changes: > 2 swap pager pageins > 2 swap pager pages paged in > 4 swap pager pageouts > 5 swap pager pages paged out > 24 vnode pager pageins > 78 vnode pager pages paged in > 0 vnode pager pageouts > 0 vnode pager pages paged out You may not have a fast enough disk. We have noticed an issue at work but only on faster controllers (e.g. certain mfi(4) drive configurations) when doing I/O to a single file like the dd command mentioned causes the buffer cache to fill up. The problem being that we can't lock the vm object to recycle pages when we hit the limit that is supposed to prevent this because all the pages in the cache are for the file (vm object) we are working on. Stephan (ups@) says this is fixed in 7. The tell-tale sign that we see is pagedaemon starts chewing up lots of CPU as the kernel tries to realign the page queues along with I/O throughput going down the toilet and being very erratic. -- John Baldwin These are the same symptoms as on a friend's system a little while back with 6.x. I forwarded him a message from this thread and he agreed, and he confirmed having an mfi.