From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262572AbTIUUfY (ORCPT ); Sun, 21 Sep 2003 16:35:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262573AbTIUUfY (ORCPT ); Sun, 21 Sep 2003 16:35:24 -0400 Received: from meryl.it.uu.se ([130.238.12.42]:63222 "EHLO meryl.it.uu.se") by vger.kernel.org with ESMTP id S262572AbTIUUfC (ORCPT ); Sun, 21 Sep 2003 16:35:02 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16238.2932.99763.591328@gargle.gargle.HOWL> Date: Sun, 21 Sep 2003 22:35:00 +0200 From: Mikael Pettersson To: Matt Hahnfeld Cc: linux-kernel@vger.kernel.org Subject: Re: SLOW machine when HIGHMEM enabled (1gb memory, kernel 2.4.22) In-Reply-To: References: X-Mailer: VM 6.90 under Emacs 20.7.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Matt Hahnfeld writes: > I have an ASUS P4P800-VM motherboard with 2 sticks of 512mb PC3200 and > a single 2.4 ghz P4 processor. The kernel is vanilla 2.4.22 configured > for SMP (hyperthreading). > > When I use a kernel with high memory support off, I get good > performance (despite not being able to use some of my memory). When I > enable CONFIG_HIGHMEM4G the remaining memory is detected, but the > machine takes a big performance hit and starts running very slow -- > ie. kernel compilation looks like it would take 5 days instead of 5 > minutes. /proc/meminfo doesn't look particularly strange and no > strange log messages show up -- everything just runs slow... > > CONFIG_HIGHMEM64G produces the same results... > > Any suggestions? Sounds like maybe the high RAM isn't cacheable. What does /proc/mtrr and dmesg look like? Have you verified that you're running the latest BIOS?