From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 11 Nov 2001 15:52:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 11 Nov 2001 15:52:23 -0500 Received: from cx662584-c.okcnc1.ok.home.com ([65.13.170.37]:53406 "EHLO cx662584-c.okcnc1.ok.home.com") by vger.kernel.org with ESMTP id ; Sun, 11 Nov 2001 15:52:09 -0500 Message-ID: <3BEEE61A.6050002@uhura.rueb.com> Date: Sun, 11 Nov 2001 14:56:58 -0600 From: Steve Bergman User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.5) Gecko/20011012 X-Accept-Language: en-us MIME-Version: 1.0 To: linux-kernel@vger.kernel.org CC: steve@rueb.com Subject: Best kernel config for exactly 1GB ram Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, I have just upgraded my athlon 1200 system to 1GB ram. I am unclear as to how I should configure the kernel for this box. The config.help says to say no to "high memory support" if the kernel will not run on a machne with more than 1GB. When I do this I notice that my available memory as reported by top is ~ 120MB less than if I say I want 4GB support. I recall that linux reserves some of the address space for itself (I thought it was just 64MB). What are the trade offs involved here? Am I better off sacrificing a bit of the physical memory for reasons of efficiency elsewhere? When I request support for up to 4GB, what exactly changes with respect to the visible virtual address space that apps see, etc? This is a desktop machine, so it's not running Oracle or anything like that. I seem to recall Linus mentioning that big databases tend to like the large (3GB) virtual address space. Any enlightenment would be greatly appreciated. Thanks, Steve Bergman steve@rueb.com