From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757721AbYFFNuh (ORCPT ); Fri, 6 Jun 2008 09:50:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756632AbYFFNuN (ORCPT ); Fri, 6 Jun 2008 09:50:13 -0400 Received: from smtp-out04.alice-dsl.net ([88.44.63.6]:40655 "EHLO smtp-out04.alice-dsl.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756449AbYFFNuM (ORCPT ); Fri, 6 Jun 2008 09:50:12 -0400 To: Andrew Morton Cc: "Denys Fedoryshchenko" , linux-kernel@vger.kernel.org Subject: Re: strange timestamp in dmesg From: Andi Kleen References: <20080605115256.M13181@visp.net.lb> <20080606031939.285679c9.akpm@linux-foundation.org> Date: Fri, 06 Jun 2008 15:49:26 +0200 In-Reply-To: <20080606031939.285679c9.akpm@linux-foundation.org> (Andrew Morton's message of "Fri, 6 Jun 2008 03:19:39 -0700") Message-ID: <87hcc6u109.fsf@basil.nowhere.org> User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/21.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-OriginalArrivalTime: 06 Jun 2008 13:42:16.0935 (UTC) FILETIME=[226C5770:01C8C7DB] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton writes: >> supports DPO and FUA >> [ 9.801761] sd 1:0:1:0: [sdc] 143374744 512-byte hardware sectors (73408 MB) >> [ 9.673388] sd 1:0:1:0: [sdc] Write Protect is off >> [ 9.673395] sd 1:0:1:0: [sdc] Mode Sense: ab 00 10 08 >> [ 9.806210] sd 1:0:1:0: [sdc] Write cache: enabled, read cache: enabled, >> supports DPO and FUA >> [ 9.806220] sdc: sdc1 >> [ 9.682136] sd 1:0:1:0: [sdc] Attached SCSI disk >> [ 13.786405] SGI XFS with large block numbers, no debug enabled >> [ 13.633457] XFS mounting filesystem sdb2 >> [ 13.724345] Starting XFS recovery on filesystem: sdb2 (logdev: internal) >> [ 14.251356] Ending XFS recovery on filesystem: sdb2 (logdev: internal) >> [ 15.379298] XFS mounting filesystem sdc1 >> [ 15.468255] Starting XFS recovery on filesystem: sdc1 (logdev: internal) >> [ 14.514314] Ending XFS recovery on filesystem: sdc1 (logdev: internal) >> [ 14.767260] warning: `squid' uses 32-bit capabilities (legacy support in use) >> [ 17.589751] e1000: eth0: e1000_watchdog: NIC Link is Up 1000 Mbps Full >> Duplex, Flow Control: RX/TX >> > > whoa, that's weird. We've seen timestamps jump forward a single hop of > ~100000 seconds, but that's all over the place. No it's expected since printk uses sched_clock() and sched clock is not synchronous between CPUs on systems without synchronized/invariant TSC (like Opteron) All sched_clock() users are expected to handle it. I always advocated just always using jiffies for printk. The only drawback would be that it won't increase in interrupt off sections, but if you have one that is longer than a jiffie then you have enough other problems. -Andi