From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756305AbYGKJJq (ORCPT ); Fri, 11 Jul 2008 05:09:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752676AbYGKJJi (ORCPT ); Fri, 11 Jul 2008 05:09:38 -0400 Received: from mtagate2.de.ibm.com ([195.212.29.151]:5118 "EHLO mtagate2.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750818AbYGKJJh (ORCPT ); Fri, 11 Jul 2008 05:09:37 -0400 Date: Fri, 11 Jul 2008 11:09:22 +0200 From: Heiko Carstens To: Thomas Gleixner , Andrew Morton Cc: Ingo Molnar , Jan Glauber , Stefan Weinhuber , linux-kernel@vger.kernel.org Subject: [PATCH] nohz: don't stop idle tick if softirqs are pending. Message-ID: <20080711090922.GA4660@osiris.boeblingen.de.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Subject: [PATCH] nohz: don't stop idle tick if softirqs are pending. From: Heiko Carstens In case a cpu goes idle but softirqs are pending only an error message is printed to the console. It may take a very long time until the pending softirqs will finally be executed. Worst case would be a hanging system. With this patch the timer tick just continues and the softirqs will be executed after the next interrupt. Still a delay but better than a hanging system. Currently we have at least two device drivers on s390 which under certain circumstances schedule a tasklet from process context. This is a reason why we can end up with pending softirqs when going idle. Fixing these drivers seems to be non-trivial. However there is no question that the drivers should be fixed. This patch shouldn't be considered as a bug fix. It just is intended to keep a system running even if device drivers are buggy. Signed-off-by: Heiko Carstens --- kernel/time/tick-sched.c | 1 + 1 file changed, 1 insertion(+) Index: linux-2.6/kernel/time/tick-sched.c =================================================================== --- linux-2.6.orig/kernel/time/tick-sched.c +++ linux-2.6/kernel/time/tick-sched.c @@ -228,6 +228,7 @@ void tick_nohz_stop_sched_tick(void) local_softirq_pending()); ratelimit++; } + goto end; } ts->idle_calls++;