From owner-freebsd-performance@FreeBSD.ORG Mon May 5 11:12:36 2003 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2A12A37B401 for ; Mon, 5 May 2003 11:12:36 -0700 (PDT) Received: from otter3.centtech.com (moat3.centtech.com [207.200.51.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id 77A3643F85 for ; Mon, 5 May 2003 11:12:35 -0700 (PDT) (envelope-from anderson@centtech.com) Received: from centtech.com (electron.centtech.com [204.177.173.173]) by otter3.centtech.com (8.12.3/8.12.3) with ESMTP id h45ICY56011316; Mon, 5 May 2003 13:12:35 -0500 (CDT) (envelope-from anderson@centtech.com) Message-ID: <3EB6A981.1030504@centtech.com> Date: Mon, 05 May 2003 13:12:17 -0500 From: Eric Anderson User-Agent: Mozilla/5.0 (X11; U; Linux i386; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Kyle Rollin References: <3801.172.182.185.39.1052141430.squirrel@bluhayz.homeunix.org> <20030505180224.M13866@xy.hartford.edu> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit cc: freebsd-performance@freebsd.org Subject: Re: Real and availible RAM X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 05 May 2003 18:12:36 -0000 Kyle Rollin wrote: > On Mon, 5 May 2003 09:30:30 -0400 (EDT), agent dero wrote > >>I have been looking through the kernel boot messages in /var/log >>while working on some custom kernel compile work, and I came across > > something > >>that I think is very interesting, but doesn't make sense. >>real memory = 100663296 (98304K bytes) >>avail memory = 94580736 (92364K bytes) >> >>This tells me that FreeBSD recognizes my 98MB of RAM, but it only >>uses 92MB? Are the 6MB of RAM that are left getting shafted, and >>just using power, but not being addressed by FreeBSD? Does this slow >>down my machine at all, I mean, is there a percentage to this? Where >>only x% of 100% RAM is availible or usable? >> > > > > > If you look at the way x86 architecture is designed (and somebody else can > feel free to correct me if I'm wrong), but system memory is often used in > the caching/shadowing of BIOS. This is where a lot of system memory often > goes before the OS is loaded - also, as Rob said, the kernel itself will > take up memory before the rest of the OS is booted. I believe that the BIOS steals the ram prior to the OS booting, so that the box does not show that as part of the total ram.. Like: CPU: VIA/IDT Unknown (1066.16-MHz 686-class CPU) Origin = "CentaurHauls" Id = 0x693 Stepping = 3 Features=0x380b13d real memory = 234815488 (223 MB) avail memory = 221167616 (210 MB) Eric -- ------------------------------------------------------------------ Eric Anderson Systems Administrator Centaur Technology Attitudes are contagious, is yours worth catching? ------------------------------------------------------------------