From mboxrd@z Thu Jan 1 00:00:00 1970 From: walimis Subject: Re: Strange behaviour on MPC5200 Date: Fri, 8 Oct 2010 10:07:18 +0800 Message-ID: <20101008020718.GA14157@ubuntu.mshome.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-rt-users@vger.kernel.org To: Detlev Zundel Return-path: Received: from mail-iw0-f174.google.com ([209.85.214.174]:58650 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750982Ab0JHCH0 (ORCPT ); Thu, 7 Oct 2010 22:07:26 -0400 Received: by iwn6 with SMTP id 6so51929iwn.19 for ; Thu, 07 Oct 2010 19:07:25 -0700 (PDT) Content-Disposition: inline In-Reply-To: Sender: linux-rt-users-owner@vger.kernel.org List-ID: On Thu, Oct 07, 2010 at 04:44:58PM +0200, Detlev Zundel wrote: >Hi, > >during tests with the rt-preempt kernel on PowerPC, I stumbled across >this really weird phenomenon of cyclictest latencies > 30ms. The test >system is a TQM5200 supported mainline, so the complete kernel source is >unmodified mainline + rt-patch. The -00001 in the kernel revision is >due to the fact that I commited the results of applying the respective >rt-patch to my local git repo. > >To debug the problem, I turned the latency tracers on and started >cyclictest with 'cyclictest -n -p80'. This looks quite good, hackbench >and the cache calibrator do not do much harm, _until_ I start to do a >ping flood from outside. Then within a few seconds the high latencies >occur. To test for a regression, I did the same test under >2.6.33.7-rt29 and 2.6.31.12-rt21. Both versions yield similar results. did you try mpc5121ads board with cyclictest test? I wonder whether it's about powerpc arch common issue or 5200 special issue. Thanks walimis > >Attached are the trace outputs for those events (gziped as they are >larger than 300KiB). > >It looks like the scheduling goes completely wrong as there is even the >idle task running before the runnable cyclictest gets scheduled in. Can >someone give me a hint on what may be wrong here? > >Thanks > Detlev > >-- >DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel >HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany >Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu@denx.de