From owner-freebsd-hackers@FreeBSD.ORG Sun Oct 3 11:08:17 2004 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 66D2C16A4CE for ; Sun, 3 Oct 2004 11:08:17 +0000 (GMT) Received: from sardine.webcom.it (gen053.n002.c03.escapebox.net [213.73.82.53]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2678543D48 for ; Sun, 3 Oct 2004 11:08:17 +0000 (GMT) (envelope-from "") Received: from [213.140.22.73] (helo=brian) by webcom.it with asmtp (Exim 3.36 #1) id 1CE4Dw-000DkS-00 for freebsd-hackers@freebsd.org; Sun, 03 Oct 2004 11:08:16 +0000 Resent-From: andrea@webcom.it Resent-Date: Sun, 3 Oct 2004 13:08:15 +0200 Resent-Message-ID: <20041003110815.GB624@webcom.it> Resent-To: freebsd-hackers@freebsd.org Date: Sun, 3 Oct 2004 13:02:33 +0200 From: Andrea Campi To: "Bruce R. Montague" Message-ID: <20041003110233.GA624@webcom.it> References: <200410020334.i923YbYB000383@mail.cruzio.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200410020334.i923YbYB000383@mail.cruzio.com> User-Agent: Mutt/1.5.6i Received: from andrea by webcom.it with asmtp (Exim 3.36 #1) id 1CE4Dw-000DkS-00; Sun, 03 Oct 2004 11:08:16 +0000 cc: freebsd-hackers@freebsd.org cc: durham@jcdurham.com Subject: Re: Sudden Reboots X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 03 Oct 2004 11:08:17 -0000 On Fri, Oct 01, 2004 at 08:34:37PM -0700, Bruce R. Montague wrote: > proposed. Instead of having a page table entry for > each page of virtual address space, these systems > have the equivalent of a page table entry for each > page of _physical_ memory. All addresses are effectively [...] > disk-block. This requires more expensive hardware > then a simple addition, but such systems only require > a page table entry for every page of physical memory. > These systems have been built from early days, but > are typically not competitive with VM systems that > require simple addition. (I think the IBM AS/400 is > the only widely-used commercial hardware using this > approach) At some point address space growth, cheap > associative lookup memories, and required page table > size may make this approach competitive. Actually, all Power and PowerPC chips have this... It's one of the reasons why IBM servers based on these chips can boast very low overheads in several areas. Bye, Andrea -- The best things in life are free, but the expensive ones are still worth a look.