From owner-freebsd-questions@FreeBSD.ORG Tue Mar 16 05:11:50 2010 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id A4618106566B for ; Tue, 16 Mar 2010 05:11:50 +0000 (UTC) (envelope-from jdc@koitsu.dyndns.org) Received: from qmta09.emeryville.ca.mail.comcast.net (qmta09.emeryville.ca.mail.comcast.net [76.96.30.96]) by mx1.freebsd.org (Postfix) with ESMTP id 8A54C8FC16 for ; Tue, 16 Mar 2010 05:11:50 +0000 (UTC) Received: from omta13.emeryville.ca.mail.comcast.net ([76.96.30.52]) by qmta09.emeryville.ca.mail.comcast.net with comcast id tf0f1d00517UAYkA9hBq2F; Tue, 16 Mar 2010 05:11:50 +0000 Received: from koitsu.dyndns.org ([98.248.46.159]) by omta13.emeryville.ca.mail.comcast.net with comcast id thBq1d0013S48mS8ZhBq3v; Tue, 16 Mar 2010 05:11:50 +0000 Received: by icarus.home.lan (Postfix, from userid 1000) id BEB499B436; Mon, 15 Mar 2010 22:11:48 -0700 (PDT) Date: Mon, 15 Mar 2010 22:11:48 -0700 From: Jeremy Chadwick To: Dan Naumov Message-ID: <20100316051148.GA73270@icarus.home.lan> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Cc: freebsd-fs@freebsd.org, freebsd-questions@freebsd.org Subject: Re: Some questions about vfs.zfs.prefetch_disable=1 and ZFS filesystem versions X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 16 Mar 2010 05:11:50 -0000 On Tue, Mar 16, 2010 at 01:40:25AM +0200, Dan Naumov wrote: > After looking at the arc_summary.pl script (found at > http://jhell.googlecode.com/files/arc_summary.pl), I have realized > that my system has set vfs.zfs.prefetch_disable=1 by default, looking > at dmesg, I see: > > ========================= > ZFS NOTICE: Prefetch is disabled by default if less than 4GB of RAM is present; > to enable, add "vfs.zfs.prefetch_disable=0" to /boot/loader.conf. > ========================= > > ...except I do have 4gb of RAM. Is this caused by integrated GPU > snatching some of my memory at boot? From dmesg: > > ========================= > real memory = 4294967296 (4096 MB) > avail memory = 4088082432 (3898 MB) > ========================= I've blogged about this problem when testing out 8.0-RC1. See the bottom third of my post for an explanation: http://koitsu.wordpress.com/2009/10/12/testing-out-freebsd-8-0-rc1/ The message is confusing/badly worded, despite having gone through numerous commits to change its wording. -- | Jeremy Chadwick jdc@parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |