Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932319AbVJCPya (ORCPT ); Mon, 3 Oct 2005 11:54:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932321AbVJCPya (ORCPT ); Mon, 3 Oct 2005 11:54:30 -0400 Received: from dvhart.com ([64.146.134.43]:64146 "EHLO localhost.localdomain") by vger.kernel.org with ESMTP id S932319AbVJCPy3 (ORCPT ); Mon, 3 Oct 2005 11:54:29 -0400 Date: Mon, 03 Oct 2005 08:54:31 -0700 From: "Martin J. Bligh" Reply-To: "Martin J. Bligh" To: David Lang Cc: Magnus Damm , Dave Hansen , Magnus Damm , linux-mm , Linux Kernel Mailing List Subject: Re: [PATCH 00/07][RFC] i386: NUMA emulation Message-ID: <93300000.1128354870@[10.10.2.4]> In-Reply-To: References: dlang@dlang.diginsite.com <83890000.1128352138@[10.10.2.4]> <86300000.1128353125@[10.10.2.4]> X-Mailer: Mulberry/2.2.1 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2187 Lines: 46 --David Lang wrote (on Monday, October 03, 2005 08:32:47 -0700): > On Mon, 3 Oct 2005, Martin J. Bligh wrote: > >> --David Lang wrote (on Monday, October 03, 2005 08:13:09 -0700): >> >>> On Mon, 3 Oct 2005, Martin J. Bligh wrote: >>> >>>> --David Lang wrote (on Monday, October 03, 2005 08:03:44 -0700): >>>> >>>>> On Mon, 3 Oct 2005, Martin J. Bligh wrote: >>>>> >>>>>> But that's not the same at all! ;-) PAE memory is the same speed as >>>>>> the other stuff. You just have a 3rd level of pagetables for everything. >>>>>> One could (correctly) argue it made *all* memory slower, but it does so >>>>>> in a uniform fashion. >>>>> >>>>> is it? I've seen during the memory self-test at boot that machines slow down noticably as they pass the 4G mark. >>>> >>>> Not noticed that, and I can't see why it should be the case in general, >>>> though I suppose some machines might be odd. Got any numbers? >>> >>> just the fact that the system boot memory test takes 3-4 times as long with 8G or ram then with 4G of ram. I then boot a 64 bit kernel on the system and never use PAE mode again :-) >>> >>> if you can point me at a utility that will test the speed of the memory in different chunks I'll do some testing on the Opteron systems I have available. unfortunantly I don't have any Xeon systems to test this on. >> >> Mmm. 64-bit uniproc systems, with > 4GB of RAM, running a 32 bit kernel >> don't really strike me as a huge market segment ;-) > > true, but there are a lot of 32-bit uniproc systems sold by Intel that have (or can have) more then 4G of ram. These are the machines I was thinking of. Does your opteron box have more than 1 socket? that'd explain it. Anyway, it shouldn't happen on any normal platform. Until we get numbers that prove that it does (and understand why), I don't think we need NUMA for PAE. M. - 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/