From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gleixner Subject: Re: NOHZ: local_softirq_pending Date: Mon, 15 Jun 2009 15:19:34 +0200 (CEST) Message-ID: References: <4A35171C.9090800@albentia.com> <8e6b7a710906141250m2a991ca9r5949e502b9976e39@mail.gmail.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Iratxo Pichel Ortiz , linux-rt-users@vger.kernel.org To: Iratxo Pichel Ortiz Return-path: Received: from www.tglx.de ([62.245.132.106]:57510 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751419AbZFONTj (ORCPT ); Mon, 15 Jun 2009 09:19:39 -0400 In-Reply-To: <8e6b7a710906141250m2a991ca9r5949e502b9976e39@mail.gmail.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: Iratxo, please do not top post. On Sun, 14 Jun 2009, Iratxo Pichel Ortiz wrote: > > I am using 2.6.30-rt16 RT Kernel on a IXP425 system. The system is running 2.6.29-rt16, right ? > > an experimental comm stack that has been working quite well with 2.6.26-rt2 > > for a very long time (> 100days). > > > > When the system boots, every 180s aprox, I see this traces in the dmesg: > > 42949422.930000] NOHZ: local_softirq_pending 02 Hmm, so something is marking the timer softirq pending, but does not wake the timer softirq. > > [42949422.940000] NOHZ: local_softirq_pending 02 > > [42949422.950000] NOHZ: local_softirq_pending 02 > > [42949422.960000] ISR HIHG LATENCY 30073 > > [42949596.920000] NOHZ: local_softirq_pending 02 > > [42949596.930000] NOHZ: local_softirq_pending 02 > > [42949596.940000] NOHZ: local_softirq_pending 02 > > [42949596.950000] NOHZ: local_softirq_pending 02 So this repeats itself roughly every 3min and stays that way for a couple of jiffies. Does your code fiddle with timers ? > > [42949596.960000] ISR HIHG LATENCY 40066 The latency is exaclty the number of NOHZ messages * 10ms. I assume you have HZ=100. Looks like your code is waiting for a timer, which does not fire due to the local_softirq_pending 02 problem. Does it work when you disable CONFIG_NOHZ ? Thanks, tglx