From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751085AbWAJOoE (ORCPT ); Tue, 10 Jan 2006 09:44:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751086AbWAJOoE (ORCPT ); Tue, 10 Jan 2006 09:44:04 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:43938 "EHLO mx3.mail.elte.hu") by vger.kernel.org with ESMTP id S1751085AbWAJOoD (ORCPT ); Tue, 10 Jan 2006 09:44:03 -0500 Date: Tue, 10 Jan 2006 15:44:12 +0100 From: Ingo Molnar To: Jens Axboe Cc: Byron Stanoszek , linux-kernel@vger.kernel.org, Andrew Morton , Linus Torvalds Subject: Re: 2G memory split Message-ID: <20060110144412.GA9295@elte.hu> References: <20060110125852.GA3389@suse.de> <20060110132957.GA28666@elte.hu> <20060110133728.GB3389@suse.de> <20060110143931.GM3389@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060110143931.GM3389@suse.de> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=AWL autolearn=no SpamAssassin version=3.0.3 0.0 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Jens Axboe wrote: > + Select the wanted split between kernel and user memory. > + > + If the address range available to the kernel is less than the > + physical memory installed, the remaining memory will be available > + as "high memory". Accessing high memory is a little more costly > + than low memory, as it needs to be mapped into the kernel first. make it _ALOT_ more clear that mere mortals should not touch this option! Also, you do not mention the userspace-VM fragmentation issues. Plus, if a user uses a 2G/2G split with more than 2G of RAM, the kernel should print a warning that it's running with a non-default split. Do the same if the user uses a non-default split with less than 960MB of RAM. > + > + Note that selecting anything but the default 3G/1G split will make > + your kernel incompatible with binary only modules. it's not 'will' but 'may', and even then, tons of .config things can break bin-only modules, so just skip this paragraph. looks good to me otherwise, with the text fixes it's: Acked-by: Ingo Molnar Ingo