From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269848AbUJMVKd (ORCPT ); Wed, 13 Oct 2004 17:10:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269847AbUJMVKd (ORCPT ); Wed, 13 Oct 2004 17:10:33 -0400 Received: from mx1.magmacom.com ([206.191.0.217]:4774 "EHLO mx1.magmacom.com") by vger.kernel.org with ESMTP id S269848AbUJMVKP (ORCPT ); Wed, 13 Oct 2004 17:10:15 -0400 Subject: Re: Clock inaccuracy seen on NVIDIA nForce2 systems From: Jesse Stockall To: Andy Currid Cc: Linux Kernel Mailing List In-Reply-To: <8E5ACAE05E6B9E44A2903C693A5D4E8A01C45AC2@hqemmail02.nvidia.com> References: <8E5ACAE05E6B9E44A2903C693A5D4E8A01C45AC2@hqemmail02.nvidia.com> Content-Type: text/plain Message-Id: <1097701839.5500.111.camel@homer.blizzard.org> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Wed, 13 Oct 2004 17:10:39 -0400 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2004-10-13 at 16:30, Andy Currid wrote: > A possible cause of this behavior is a clock synchronization issue that > can arise on some nForce2 systems when interrupts are routed through the > IOAPIC, and Spread Spectrum (SS) clocking is enabled. Under certain > conditions, this can cause the IOAPIC to issue multiple interrupts to > the CPU when it should have issued only one. > > If you are experiencing clock inaccuracy on nForce2 hardware, take the > following steps to determine if this issue may be the cause: > > 1. Determine if the hardware you are using may be affected by this > problem. The problem is limited to MCP2 and MCP2-T hardware; it does > not affect MCP2-S or any nForce3 hardware. MCP2 and MCP2-T hardware > may be identified by the PCI device ID of the ISA bridge, which is > 0x0060 for these devices. > > To read the bridge device ID, use 'lspci -n -s 0:1.0' . The output > should be of the form '0000:00:01.0 Class 0601: 10de:0060 (rev a3)'. > The device ID of the bridge in this example is "0060" following the > NVIDIA PCI vendor ID "10de". > > If your ISA bridge device ID is not 0x0060, then this issue is not > the cause of any clock inaccuracy you are experiencing. lspci -n -s 0:1.0 output: 0000:00:01.0 Class 0601: 10de:0060 (rev a3) > > 2. Otherwise, examine the output from 'cat /proc/interrupts'. If IRQ0 > (the timer) is shown to be in PIC mode rather than IOAPIC mode, then > this issue is not the cause of any clock inaccuracy you are > experiencing. > cat /proc/interrupts output: 0: 179117760 IO-APIC-edge timer > 3. Otherwise, reboot your system and enter BIOS SETUP. Check if your > BIOS has a Front Side Bus (FSB) Spread Spectrum (SS) clocking option. > On many systems, this option is located in the "Advanced Chipset > Features" menu. If the option is present and enabled, disable it. > Boot Linux and observe the system clock over several hours to verify > if this has improved its accuracy. > Both Front Side Bus and AGP spread spectrum are disabled. The system is running 2.6.9-rc4 and has been up for 2 days. I'm showing an offset of -32 seconds and growing. Jesse -- Jesse Stockall