From owner-freebsd-isp@FreeBSD.ORG Wed Dec 10 16:26:32 2003 Return-Path: Delivered-To: freebsd-isp@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E158016A4CE; Wed, 10 Dec 2003 16:26:32 -0800 (PST) Received: from spmler2.mail.eds.com (spmler2.mail.eds.com [194.128.225.188]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2E0CD43D09; Wed, 10 Dec 2003 16:26:31 -0800 (PST) (envelope-from thomas.sparrevohn@eds.com) Received: from spmlir2.mail.eds.com (spmlir2.mail.eds.com [205.191.69.42]) by spmler2.mail.eds.com (8.12.10/8.12.9) with ESMTP id hBB0QR5P010379; Thu, 11 Dec 2003 00:26:27 GMT Received: from spmlir2.mail.eds.com (localhost [127.0.0.1]) by spmlir2.mail.eds.com (8.11.6p3/8.11.6) with ESMTP id hBB0QRs08295; Thu, 11 Dec 2003 00:26:27 GMT Received: from ukspm104.exemhub.exch.eds.com ([204.230.90.155]) by spmlir2.mail.eds.com (8.11.6p3/8.11.6) with ESMTP id hBB0QRS08289; Thu, 11 Dec 2003 00:26:27 GMT Received: by ukspm104.exemhub.exch.eds.com with Internet Mail Service (5.5.2657.72) id ; Thu, 11 Dec 2003 00:26:21 -0000 Message-ID: <2946E9F05C8DD511A7DC0002A5608CE401143D3F@gbchm201.exgb01.exch.eds.com> From: "Sparrevohn, Thomas" To: bv@wjv.com, freebsd-isp@freebds.org Date: Thu, 11 Dec 2003 00:26:20 -0000 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2657.72) Content-Type: text/plain cc: nbari@unixmexico.com cc: freebsd-isp@freebsd.org cc: freebsd-hackers@freebsd.org Subject: RE: adding more ram X-BeenThere: freebsd-isp@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Internet Services Providers List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Dec 2003 00:26:33 -0000 The same was true for 10.20 and 11 Versions of HPUX - I believe there once was I very long going debate when the "new" FreeBSD vm was made on the issue. The fundamental question at the time was what to do when you run out of swap/vm space. The 1-1 backing of swap space was seen as a way to avoid that you have resort to kill random processes in order to free up space and the tradition with the 2-1 swap ratio used to have "a performance reason" in the initial Unix Swap and paging implementations. I can't seem to recall the actual reason -----Original Message----- From: owner-freebsd-hackers@freebsd.org [mailto:owner-freebsd-hackers@freebsd.org] On Behalf Of Bill Vermillion Sent: 10 December 2003 14:41 To: freebsd-isp@freebds.org Cc: nbari@unixmexico.com; freebsd-isp@freebsd.org; freebsd-hackers@freebsd.org Subject: Re: adding more ram While normally not able to pour water out of a boot with instructions on the heel, on Wed, Dec 10, 2003 at 02:41 our dear friend Mike Silbersack uttered this load of codswallop: Just one slight addendum here. > I'm replying because I want to answer your real question. > The notion of swap = 2 x ram is an old one, and is no longer > applicable. (Some) older VM systems used very simplistic swapping > mechanisms, which required entire processes to be swapped, thereby > requiring large amounts of swap space. FreeBSD (and other modern OSes) > page out to the swap file in increments of 4K pages, and do so in a > flexible manner. As a result, you should always have *some* swap space > to handle overload cases, but it's not necessary to keep any specific > ram to swap ratio. Systems such as the Irix I used before moving the servers to FBSD around 1996 - reserverd swap space for applications when the application started up so those needed large swap space. Often it was never used, but the design allocated it anyway. Bill -- Bill Vermillion - bv @ wjv . com _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"