From owner-freebsd-current@FreeBSD.ORG Thu Jan 22 23:27:56 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 61CD016A4CE for ; Thu, 22 Jan 2004 23:27:56 -0800 (PST) Received: from server.vk2pj.dyndns.org (c211-30-75-229.belrs2.nsw.optusnet.com.au [211.30.75.229]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4D33943D58 for ; Thu, 22 Jan 2004 23:27:52 -0800 (PST) (envelope-from peterjeremy@optushome.com.au) Received: from server.vk2pj.dyndns.org (localhost.vk2pj.dyndns.org [127.0.0.1])i0N7RfPf059826 for ; Fri, 23 Jan 2004 18:27:41 +1100 (EST) (envelope-from peter@server.vk2pj.dyndns.org) Received: (from peter@localhost) by server.vk2pj.dyndns.org (8.12.10/8.12.10/Submit) id i0N7ReZB059825 for freebsd-current@freebsd.org; Fri, 23 Jan 2004 18:27:40 +1100 (EST) (envelope-from peter) Date: Fri, 23 Jan 2004 18:27:40 +1100 From: Peter Jeremy To: freebsd-current@freebsd.org Message-ID: <20040123072740.GA53327@server.vk2pj.dyndns.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Subject: Re: MFS question - FreeBSD 5.2-CURRENT 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: Fri, 23 Jan 2004 07:27:56 -0000 On Thu, Jan 22, 2004 at 09:16:14PM +0000, Rob MacGregor wrote: >>Note that softupdates will not perform any physical writes for short- >>lived (say less than 30 seconds) files. > >That's worth knowing - do you know how big the buffer is likely to be? I'm >thinking worst case of a 10 MB zip in an email, maybe expanding to 20 MB. As someone else mentioned, there is no fixed size. The kernel will allocate RAM to the buffer as well as running processes. For some background on softupdates, have a look at: Gregory R. Ganger's original paper on SoftUpdates: http://www.ece.cmu.edu/~ganger/papers/CSE-TR-254-95/ Kirk McKusick's papers on SoftUpdates (which discusses the FreeBSD implementation: http://www.mckusick.com/softdep/index.html Peter