From owner-freebsd-fs@FreeBSD.ORG Thu Apr 14 11:13:20 2011 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 25C48106566B for ; Thu, 14 Apr 2011 11:13:20 +0000 (UTC) (envelope-from s.seira@cdmon.com) Received: from correo.cdmon.com (correo.cdmon.com [212.36.82.9]) by mx1.freebsd.org (Postfix) with ESMTP id CE8878FC20 for ; Thu, 14 Apr 2011 11:13:19 +0000 (UTC) Received: from genocida (localhost.cdmon.com [127.0.0.1]) by correo.cdmon.com (Postfix) with ESMTP id 68284130CF3 for ; Thu, 14 Apr 2011 12:54:28 +0200 (CEST) Received: from antispam (localhost.cdmon.com [127.0.0.1]) by correo.cdmon.com (Postfix) with ESMTP id 191F2130C2B for ; Thu, 14 Apr 2011 12:54:28 +0200 (CEST) Received: from [192.168.0.30] (155.Red-88-2-251.staticIP.rima-tde.net [88.2.251.155]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by correo.cdmon.com (Postfix) with ESMTP id BC7F9130C1C; Thu, 14 Apr 2011 12:54:27 +0200 (CEST) Message-ID: <4DA6D269.1040702@cdmon.com> Date: Thu, 14 Apr 2011 12:54:33 +0200 From: Sergi Seira User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.9) Gecko/20100515 Lightning/1.0b1 Icedove/3.0.4 MIME-Version: 1.0 To: Kirk McKusick References: <201104131505.p3DF5tPa015944@chez.mckusick.com> In-Reply-To: <201104131505.p3DF5tPa015944@chez.mckusick.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-fs@freebsd.org Subject: Re: background fsck high load on 8.1 X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 14 Apr 2011 11:13:20 -0000 Hello, thanks for the explanation, I can confirm this behaviour on serveral upgraded boxes. We'll look forward to journaled soft updates or maybe switching to zfs. Anyway it isn't happening that much, only on hard resets. Regards, Sergi On 13/04/11 17:05, Kirk McKusick wrote: >> Date: Tue, 12 Apr 2011 15:14:42 +0200 >> From: Sergi Seira >> To: freebsd-current@freebsd.org >> Subject: background fsck high load on 8.1 >> >> Hello, >> >> We've experienced that background fsck on 8.1 degrades server >> performance on a higher degree than in previous fbsd versions (6.3, >> 7.3; amd64). >> >> We've noticed it after upgrading - same hardware - to a 8.1-RELEASE. >> Now, performance of other services (i.e. apache, mysql) during a >> background fsck falls miserably. >> >> Is there any way to calm fsck down?, nice(1)?, some sysctl? >> >> We have also gmirror, but we prevent to rebuild it if there is a >> fsck running in background. >> >> Thanks for your help, >> regards, >> Sergi > > This is the first report that I have heard of the higher level of > slowdown by background fsck on 8.X systems. My guess is that it > comes about from work done to make the I/O subsystem faster which > in turn allows fsck to have a higher impact. > > For a period we were working on a kernel feature (associated with > nice) that would allow the system to throttle I/O activity for a > given process. It turns out to be a much harder problem than it at > first appears. We set this aside when we got journaled soft updates > working as they eliminate the need for background fsck. While > journaled soft updates are too big of a change to be merged back > into the 8.X tree, we do expect them to be used by default on 9.X > systems. > > Kirk McKusick -- ---8<-------------------- Sergi Seira i Espunya Departament de Sistemes s.seira@cdmon.com www.cdmon.com 93 567 7577 902 364 138 91 182 2767 ext:161 -------------------->8---