From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765816AbXGYNU0 (ORCPT ); Wed, 25 Jul 2007 09:20:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761993AbXGYNUL (ORCPT ); Wed, 25 Jul 2007 09:20:11 -0400 Received: from smtp4-g19.free.fr ([212.27.42.30]:57152 "EHLO smtp4-g19.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761975AbXGYNUJ (ORCPT ); Wed, 25 Jul 2007 09:20:09 -0400 Message-ID: <46A74E05.50504@free.fr> Date: Wed, 25 Jul 2007 15:20:05 +0200 From: John Sigler User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.8) Gecko/20061108 SeaMonkey/1.0.6 MIME-Version: 1.0 To: Ingo Molnar CC: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Pin-pointing the root of unusual application latencies References: <469600F7.3060603@free.fr> <20070723095357.GA886@elte.hu> <46A4B7C2.1070304@free.fr> <20070723160442.GA7995@elte.hu> <46A5B8E3.4060004@free.fr> <46A74A58.1070704@free.fr> <20070725130536.GA12334@elte.hu> In-Reply-To: <20070725130536.GA12334@elte.hu> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org (Dropping oprofile-list@lists.sourceforge.net) Ingo Molnar wrote: > John Sigler wrote: > >>> With a pair of the following in the middle: >>> >>> softirq--4 0.... 670us : call_rcu (rt_run_flush) >>> softirq--4 0D..1 670us : __rcu_advance_callbacks (call_rcu) > >> Any idea what went wrong in the above function trace? Why is the >> kernel spinning in circles that way? > > does your test-app have higher priority than softirq--4 ? PID 4 is [softirq-timer/0] and has priority 50 in SCHED_FIFO. My process has priority 80 in SCHED_RR. It is waiting for IRQ10. My user-space app has higher priority than everything except PID 2 which is [posix_cpu_timer] Is this a priority inversion issue? Regards.