Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964898AbVJ0BIK (ORCPT ); Wed, 26 Oct 2005 21:08:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964932AbVJ0BIK (ORCPT ); Wed, 26 Oct 2005 21:08:10 -0400 Received: from ms-smtp-01.nyroc.rr.com ([24.24.2.55]:25030 "EHLO ms-smtp-01.nyroc.rr.com") by vger.kernel.org with ESMTP id S964898AbVJ0BIJ (ORCPT ); Wed, 26 Oct 2005 21:08:09 -0400 Subject: Re: 2.6.14-rc4-rt7 From: Steven Rostedt To: john stultz Cc: William Weston , Rui Nuno Capela , george@mvista.com, Ingo Molnar , Fernando Lopez-Lezcano , Mark Knecht , david singleton , Thomas Gleixner , linux-kernel@vger.kernel.org, cc@ccrma.Stanford.EDU In-Reply-To: <1130373953.27168.370.camel@cog.beaverton.ibm.com> References: <1129852531.5227.4.camel@cmn3.stanford.edu> <20051021080504.GA5088@elte.hu> <1129937138.5001.4.camel@cmn3.stanford.edu> <20051022035851.GC12751@elte.hu> <1130182121.4983.7.camel@cmn3.stanford.edu> <1130182717.4637.2.camel@cmn3.stanford.edu> <1130183199.27168.296.camel@cog.beaverton.ibm.com> <20051025154440.GA12149@elte.hu> <1130264218.27168.320.camel@cog.beaverton.ibm.com> <435E91AA.7080900@mvista.com> <20051026082800.GB28660@elte.hu> <435FA8BD.4050105@mvista.com> <435FBA34.5040000@mvista.com> <435FEAE7.8090104@rncbc.org> <1130371042.21118.76.camel@localhost.localdomain> <1130373953.27168.370.camel@cog.beaverton.ibm.com> Content-Type: text/plain Organization: Kihon Technologies Date: Wed, 26 Oct 2005 21:07:24 -0400 Message-Id: <1130375244.21118.91.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1788 Lines: 47 On Wed, 2005-10-26 at 17:45 -0700, john stultz wrote: > Ok, I've reproduced the issue. > > However, running a clock_gettime(CLOCK_MONOTONIC) inconsistency check > results in no failures, but triggers this code in the kernel. > > Looking at the code, these may be false positives. The bit that is > complaining I believe Ingo added to get_monotonic_clock_ts() in > kernel/time/timeofday.c. However I don't see any locking that > serializes the writes the prev in the same order as the > get_monotonic_clock_ts is called. > > I'm still digging and will send out some mail when I figure out whats > wrong. Hmm, I'm wondering if these are a false positive. Being a fully preemptible kernel, we could be preempted between taking now and getting prev, so the prev could be updated to a time after now and show a warp. William and Rui, could you try this patch and see if you still get the warnings. Although I doubt this is really the problem, since I can't see how it would cause clusters of these messages. -- Steve Index: linux-2.6.14-rc5-rt7/kernel/time/timeofday.c =================================================================== --- linux-2.6.14-rc5-rt7.orig/kernel/time/timeofday.c 2005-10-26 16:57:03.000000000 -0400 +++ linux-2.6.14-rc5-rt7/kernel/time/timeofday.c 2005-10-26 21:03:22.000000000 -0400 @@ -243,8 +243,8 @@ ns_to_timespec(ts, mc); - now = timespec_to_ktime(*ts); prev = per_cpu(prev_mono_time, cpu); + now = timespec_to_ktime(*ts); prev_st = per_cpu(prev_system_time, cpu); curr_st = system_time; - 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/