From owner-freebsd-current@FreeBSD.ORG Thu Jul 28 21:13:48 2005 Return-Path: X-Original-To: freebsd-current@FreeBSD.org 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 93E3D16A420; Thu, 28 Jul 2005 21:13:48 +0000 (GMT) (envelope-from julian@elischer.org) Received: from postoffice.vicor-nb.com (postoffice.vicor.com [69.26.56.52]) by mx1.FreeBSD.org (Postfix) with ESMTP id A4EE043D4C; Thu, 28 Jul 2005 21:13:45 +0000 (GMT) (envelope-from julian@elischer.org) Received: from localhost (localhost [127.0.0.1]) by postoffice.vicor-nb.com (Postfix) with ESMTP id 3869D4CE975; Thu, 28 Jul 2005 14:13:45 -0700 (PDT) Received: from postoffice.vicor-nb.com ([127.0.0.1]) by localhost (postoffice.vicor-nb.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 51165-06; Thu, 28 Jul 2005 14:13:44 -0700 (PDT) Received: from [208.206.78.97] (julian.vicor-nb.com [208.206.78.97]) by postoffice.vicor-nb.com (Postfix) with ESMTP id 9C6894CE96E; Thu, 28 Jul 2005 14:13:44 -0700 (PDT) Message-ID: <42E94A88.4010603@elischer.org> Date: Thu, 28 Jul 2005 14:13:44 -0700 From: Julian Elischer User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7.8) Gecko/20050629 X-Accept-Language: en, hu MIME-Version: 1.0 To: Scott Long References: <42E88135.30603@elischer.org> <42E88F2B.5000108@elischer.org> <20050728082844.GW46538@darkness.comp.waw.pl> <42E898A6.6010803@elischer.org> <20050728115251.GA20091@beatrix.daedalusnetworks.priv> <20050728135613.GD46538@darkness.comp.waw.pl> <42E93EE1.2090009@elischer.org> <42E94310.20806@samsco.org> In-Reply-To: <42E94310.20806@samsco.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at postoffice.vicor.com Cc: re@FreeBSD.org, FreeBSD Current , Pawel Jakub Dawidek , Giorgos Keramidas Subject: Re: 6.0 VFS/VM over-runs. Was: Apparent strange disk behaviour in 6.0 X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 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: Thu, 28 Jul 2005 21:13:48 -0000 I thought the original description was good.. file data written to cache to await output to disk is allowed to grow to the extent that running programs are swapped out. (or at least paged out). here's a simple experiment that takes 1 minute to show the problem. Best with a system with 2 disk drives (or a disk and a raid in my case) boot to single user. mount a large partition that has some room.. hopefully several times the space of all RAM. . do: dd if=/dev/zero of=/${mountpoint}/bigfile bs=128k count=1000000 & iostat 1 notice that dd dies with "not enough swapspace" after some number of seconds. (there is no swap attached). also notice that until the crash, IO speed was max for the disk. then add swap and do it again. notice that at teh point where dd previously crashed, the swap disk springs into life and disk IO on your main disk goes into the toilet. notice that dd gets swapped out. (!!!!) when the disk recovers enough, dd pages back in and creates more IO but in teh mean time there is no IO going on to the disk.. (watch the LEDs). Scott Long wrote: > Julian Elischer wrote: > >> This is an absolute show stopper for 6.0 >> > > Can you distill this down to a problem description that we can track? > > Scott