From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: 2.6.20-rc6-mm3 Date: Wed, 31 Jan 2007 14:22:45 +0100 Message-ID: <20070131132245.GA26066@elte.hu> References: <20070129204528.eb8d695e.akpm@osdl.org> <45BFC442.5000903@gmail.com> <20070130142714.9f8dd5da.akpm@osdl.org> <200701310155.05474.fzu@wemgehoertderstaat.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx2.mail.elte.hu ([157.181.151.9]:54434 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933251AbXAaNYo (ORCPT ); Wed, 31 Jan 2007 08:24:44 -0500 Content-Disposition: inline In-Reply-To: <200701310155.05474.fzu@wemgehoertderstaat.de> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Karsten Wiese Cc: Andrew Morton , Maciej Rutecki , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org * Karsten Wiese wrote: > Similar weirdness here on rc6-mm2 and rc6-rt*: resume from disk waits > unduly long. i'm wondering whether the jiffies update fix from Thomas fixes this bug for you. If not then do you have a serial console enabled? > Some waiting times from rc6-rt6 from memory: > > Config | HZ | NO_HZ + HRESTIMERS > cmos clock unchanged | 2s | 6s > cmos clock += 10min | | 2 minutes > cmos clock += 2 month | 20s | > 4minutes, test interrupted i've seen something like this on -rt (and incorrectly attributed it to -rt) when running on a system which has a serial port and which has a kernel console on that serial port. What happens is that after resume (and straight after console suspend) every serial character printed takes /alot/ of time - and resume does print a number of kernel messages to the console. I didnt get any further in debugging this though, but disabling the serial console made the problem go away. a possibly related thing: the serial code is sensitive to jiffies updates and timers, i saw that during early revisions of the dynticks code - but the specifics escape me. the slowdown could also be something like the kernel somehow wrapping around jiffies and thus doing /alot/ of jiffy ticks? Or it could be a miscalculation in the amount of jiffies that need updating, resulting in a similar number of loops in the jiffy update code. (i'll try to figure out this regression - but wanted to describe to you the known things so far, maybe you'll figure it out faster than me.) Ingo