Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760264AbXKCXan (ORCPT ); Sat, 3 Nov 2007 19:30:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755213AbXKCXaf (ORCPT ); Sat, 3 Nov 2007 19:30:35 -0400 Received: from terminus.zytor.com ([198.137.202.10]:55815 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752939AbXKCXaf (ORCPT ); Sat, 3 Nov 2007 19:30:35 -0400 Message-ID: <472D0488.7040404@zytor.com> Date: Sat, 03 Nov 2007 16:30:16 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.5 (X11/20070727) MIME-Version: 1.0 To: =?ISO-8859-1?Q?Bo_Brant=E9n?= CC: linux-kernel@vger.kernel.org, mpm@selenic.com Subject: Re: x86_64 ten times slower than i386 References: <20071103162640.GS17536@waste.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 870 Lines: 21 Bo Brant?n wrote: > On Sat, 3 Nov 2007, Matt Mackall wrote: > >> This is typically due to a problem with the setup of your MTRRs. Try >> booting with mem=nnnM where nnn is some number smaller than your >> actual amount of memory. > > Thank you for that advice, the system has 4GB and if I boot with > mem=3072M it will run as fast as normal while if I don't use the mem > option it will run 10 times slower, however if I use a figure like > mem=3500M the kernel will panic, is there any way to determine the > highest usable figure without try and error? Yes, look at how your MTRRs are set up (cat /proc/mtrr). -hpa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/