Return-path: Received: from nebensachen.de ([195.34.83.29]:46835 "EHLO mail.nebensachen.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753552AbYJKUa5 (ORCPT ); Sat, 11 Oct 2008 16:30:57 -0400 From: Elias Oltmanns To: Thomas Gleixner Cc: Jiri Slaby , linux-wireless@vger.kernel.org Subject: Re: ath5k: kernel timing screwed - due to unserialised register access? References: <87k5cm3ee2.fsf@denkblock.local> <87d4id3jmr.fsf@denkblock.local> <87skr8h1de.fsf@denkblock.local> <87hc7ot804.fsf@denkblock.local> <87myhfnwne.fsf@denkblock.local> <87k5cgg87j.fsf@denkblock.local> <87abdck6sn.fsf@denkblock.local> Date: Sat, 11 Oct 2008 22:30:17 +0200 Message-ID: <87k5ceeuxy.fsf@denkblock.local> (sfid-20081011_223104_277469_BAAC6D6A) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-wireless-owner@vger.kernel.org List-ID: Thomas Gleixner wrote: > On Fri, 10 Oct 2008, Thomas Gleixner wrote: >> On Fri, 10 Oct 2008, Elias Oltmanns wrote: [...] >> > This particular one is in >> > drivers/net/wireless/ath5k/phy.c:ath5k_hw_noise_floor_calibration() >> > which is called from ath5k_calibrate(), the callback executed every ten >> > seconds in softirq context. Could this have anything to do with our >> >> That makes sense. The timer expires early events are multiples of 10s >> apart. > > Ok, I thought more about it and aside of the fact that the ath5k is > doing something nasty, you unearthed a weakness in the broadcast code. > > Can you please try the following: > > Compile the acpi_processor module in to the kernel > (CONFIG_ACPI_PROCESSOR=y) and add processor.max_cstate=1 to the kernel > command line. If I analysed the problem correctly this will make the > jiffies problem go away. I'm working on a fix. Spot on, it does go away regardless whether NO_HZ or HIGH_RES are enabled or disabled. Looking forward to testing your fix ;-). Regards, Elias