From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751746AbXCDNki (ORCPT ); Sun, 4 Mar 2007 08:40:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751754AbXCDNki (ORCPT ); Sun, 4 Mar 2007 08:40:38 -0500 Received: from www.osadl.org ([213.239.205.134]:38038 "EHLO mail.tglx.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751746AbXCDNkh (ORCPT ); Sun, 4 Mar 2007 08:40:37 -0500 Subject: Re: [PATCH] highres: Do not run the TIMER_SOFTIRQ after switching to highres mode From: Thomas Gleixner Reply-To: tglx@linutronix.de To: Andres Salomon Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton In-Reply-To: <45EAC5B1.2060306@debian.org> References: <45E8E2F8.1030102@debian.org> <1172912540.24738.108.camel@localhost.localdomain> <45EAAA21.4040803@debian.org> <1173013794.24738.130.camel@localhost.localdomain> <45EAC5B1.2060306@debian.org> Content-Type: text/plain Date: Sun, 04 Mar 2007 14:23:50 +0100 Message-Id: <1173014630.24738.132.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2007-03-04 at 08:12 -0500, Andres Salomon wrote: > Thomas Gleixner wrote: > >>> The question is, how the tick timer gets enqueued in the softirq queue. > >>> Can you isolate the codepath, where this happens ? > > > > The TIMER_SOFTIRQ runs the hrtimers during bootup until a usable > > clocksource and clock event sources are registered. The switch to high > > resolution mode happens inside of the TIMER_SOFTIRQ, but runs the > > softirq afterwards. That way the tick emulation timer, which was set up > > in the switch to highres might be executed in the softirq context, which > > is a BUG. The rbtree has not to be touched by the softirq after the > > highres switch. > > > > And an additional request, just to make it explicit that we should not > have any NO_SOFTIRQ callbacks in the tree; BUG out if we encounter such > a thing. > > Signed-off-by: Andres Salomon Acked-by: Thomas Gleixner