Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756637AbXKFTk5 (ORCPT ); Tue, 6 Nov 2007 14:40:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754586AbXKFTkt (ORCPT ); Tue, 6 Nov 2007 14:40:49 -0500 Received: from 1wt.eu ([62.212.114.60]:3724 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754353AbXKFTks (ORCPT ); Tue, 6 Nov 2007 14:40:48 -0500 Date: Tue, 6 Nov 2007 20:40:09 +0100 From: Willy Tarreau To: "H. Peter Anvin" Cc: Andi Kleen , Ray Lee , Bo =?iso-8859-1?Q?Brant=E9n?= , Andrew Morton , Jesse Barnes , linux-kernel@vger.kernel.org Subject: Re: x86_64 ten times slower than i386 Message-ID: <20071106194009.GC1045@1wt.eu> References: <20071103162640.GS17536@waste.org> <2c0942db0711050832t5207ea8bib1f75e59e071ade2@mail.gmail.com> <20071106002647.GA27182@one.firstfloor.org> <472FC130.40605@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <472FC130.40605@zytor.com> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1137 Lines: 27 On Mon, Nov 05, 2007 at 05:19:44PM -0800, H. Peter Anvin wrote: > Andi Kleen wrote: > >>Jesse Barnes (cc:d) wrote a patch to address this, I think (x86: trim > >>memory not covered by WB MTRRs), but as far as I can tell it hasn't > >>been merged yet. System is Intel, 4gb of RAM. > > > >It wasn't merged because it broke booting on some systems. > >Besides the memory would be still lost -- all it did was to automate > >the "mem=XXXX" line. > > There really are only two ways to deal with this -- drop the memory > (which should be automated, and a warning printed) or adjust the MTRRs. > The problem is that at some point we run out of MTRRs, partially > because they're masks instead of base/limit. Just out of curiosity, what would be the problem if the MTRRs covered more than the memory size ? For instance, instead of having 512 MB at 4G, why not have 1G at 4G ? regards, Willy - 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/