From owner-freebsd-current@FreeBSD.ORG Sun Apr 13 18:17:12 2003 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 D3B7637B401 for ; Sun, 13 Apr 2003 18:17:12 -0700 (PDT) Received: from smtp.acd.net (smtp.acd.net [207.179.64.154]) by mx1.FreeBSD.org (Postfix) with ESMTP id AD43E43FDD for ; Sun, 13 Apr 2003 18:17:11 -0700 (PDT) (envelope-from taxman@ACD.NET) Received: from 207.179.66.21 ([207.179.66.21]) by smtp.acd.net with Microsoft SMTPSVC(5.0.2195.5329); Sun, 13 Apr 2003 21:18:03 -0400 From: taxman To: Lucky Green , Bruce Evans Date: Sun, 13 Apr 2003 21:13:38 -0400 User-Agent: KMail/1.5 References: <20030410230113.M81717@pakastelohi.cypherpunks.to> <20030411182925.A3507@gamplex.bde.org> <20030412213940.O6477@pakastelohi.cypherpunks.to> In-Reply-To: <20030412213940.O6477@pakastelohi.cypherpunks.to> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200304132113.39032.taxman@acd.net> X-OriginalArrivalTime: 14 Apr 2003 01:18:04.0506 (UTC) FILETIME=[B2E663A0:01C30223] cc: freebsd-current@freebsd.org Subject: Re: options NO_SWAPPING, still wants swap 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: Mon, 14 Apr 2003 01:17:13 -0000 On Saturday 12 April 2003 03:42 pm, Lucky Green wrote: > On Fri, 11 Apr 2003, Bruce Evans wrote: > > On Thu, 10 Apr 2003, Lucky Green wrote: > > > I compiled a kernel with "options NO_SWAPPING", yet CURRENT still > > > attempts to allocate swap space: > > > > NO_SWAPPING has nothing to do with not allocating swap space. It > > prevents swapping of upages and stack pages only. > > > > Unfortunately, NOTES' description of NO_SWAPPING says that it disables > > swapping without explaining what swapping is (it is just swapping of > > upages and stack, and has nothing to do with generic VM paging). > > NO_SWAPPING is documented mainlly in the commitlog for the change that > > added it: > > Perhaps a kind comitter could modify NOTES to help make users aware that > NO_SWAPPING does not disable swapping of memory to disk and to look to man but it does disable swapping. The confusing part is that the terms swapping and paging mean different things and both use swap space. Paging is just the normal movement of pages between main memory and swap space. Pages get paged out to most effectively use memory for other processes. Swapping is the more serious case of when there is a shortage of memory that the pagedaemon cannot provide for . The swapper completely removes a process from main memory. > rc.conf for information about the latter? I am fully in support of the difference being documented in NOTES As a side note the value of having swap space even if you have enough main memory is being able to get crash dumps. Information taken from McKusik et al, Design and Implementation... Tim