Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261200AbVE2Bcz (ORCPT ); Sat, 28 May 2005 21:32:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261204AbVE2Bcz (ORCPT ); Sat, 28 May 2005 21:32:55 -0400 Received: from dream.eng.uci.edu ([128.195.164.137]:26889 "EHLO dream.dream.eng.uci.edu") by vger.kernel.org with ESMTP id S261200AbVE2Bcx (ORCPT ); Sat, 28 May 2005 21:32:53 -0400 From: "Liangchen Zheng" To: Subject: The values of gettimeofday() jumps. Date: Sat, 28 May 2005 18:37:10 -0700 Message-ID: <000201c563ee$eed993d0$85a4c380@dream.eng.uci.edu> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.2627 In-Reply-To: <20050528231737.805020000@nd47.coderock.org> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 Importance: Normal X-OriginalArrivalTime: 29 May 2005 01:37:12.0609 (UTC) FILETIME=[EFC70110:01C563EE] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1329 Lines: 29 Hello, We have several SMP machines (Tyan Tiger MPX motherboard, 2 AthlonMP 1900+ CPU, linux-2.4.21-20.EL). When running some time sensitive programs, I observed that the values of gettimeofday () jumped sometimes on a couple of machines (other machines are fine), from several hundreds milliseconds to a couple of seconds. I searched online and tried to figure out why this happened. It seems there are a lot of people who complained about the clock drift issue of gettimeofday () on SMP machines. But I still could not get the answers about what is the exact cause of this issue and how to fix it. Could somebody tell me some clues? Can this be solved by upgrading the kernel to 2.6? Thanks a lot. By the way, I have read Linux SMP HOWTO and the following documents. http://seclists.org/lists/linux-kernel/2002/Jun/1524.html http://seclists.org/lists/linux-kernel/2002/Jun/1550.html http://alphalinux.org/archives/linux-alpha/April2000/0015.html I could not get enough clues from them yet, maybe because my limited knowledge about the kernel. Regards, [Liangchen Zheng] - 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/