From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751239AbWGHWNL (ORCPT ); Sat, 8 Jul 2006 18:13:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751184AbWGHWNL (ORCPT ); Sat, 8 Jul 2006 18:13:11 -0400 Received: from stat9.steeleye.com ([209.192.50.41]:48305 "EHLO hancock.sc.steeleye.com") by vger.kernel.org with ESMTP id S1751239AbWGHWNJ (ORCPT ); Sat, 8 Jul 2006 18:13:09 -0400 Subject: Re: Hang and Soft Lockup problems with generic time code From: James Bottomley To: john stultz Cc: Andrew Morton , linux-kernel , Roman Zippel In-Reply-To: <1152395222.8636.7.camel@localhost> References: <1152313879.3866.53.camel@mulgrave.il.steeleye.com> <1152315579.7493.9.camel@localhost.localdomain> <1152333404.3866.80.camel@mulgrave.il.steeleye.com> <1152395222.8636.7.camel@localhost> Content-Type: text/plain Date: Sat, 08 Jul 2006 17:13:05 -0500 Message-Id: <1152396785.12020.33.camel@mulgrave.il.steeleye.com> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-4.fc4) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2006-07-08 at 14:47 -0700, john stultz wrote: > > Well, what I was seeing was that > > > > clocksource_read(clock) - clock->cycle_last > > > > is returning a value about 200 x clock->cycle_interval > > That then would be ~200 ticks. Is this at HZ=1000 ? no, 250. > > According to the debugging printks I put into update_wall_time(). I was > > assuming this was caused by a jump in the TSC count, but I suppose it > > could also be cause by spurious alterations to cycle_last or other > > effects I haven't traced. > > Since this issue effected both the TSC and ACPI PM timer, I'd more > likely suspect something is holding off the timer interrupt. This could > be some kernel code like a driver, or it could be something like an SMI > from the BIOS. The driver takes only ~10s to insert and these cycle jumps occur within that time frame, so it's not a real 200s. The timer system has somehow manufactured the cycle jump. James