From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966347AbXDGVbz (ORCPT ); Sat, 7 Apr 2007 17:31:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S966350AbXDGVbz (ORCPT ); Sat, 7 Apr 2007 17:31:55 -0400 Received: from gateway-1237.mvista.com ([63.81.120.158]:20285 "EHLO gateway-1237.mvista.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966347AbXDGVbz (ORCPT ); Sat, 7 Apr 2007 17:31:55 -0400 Subject: Re: [PATCH] timekeeping: drop irq-context clocksource polling From: Daniel Walker To: tglx@linutronix.de Cc: Andrew Morton , linux-kernel@vger.kernel.org, johnstul@us.ibm.com, mingo@elte.hu In-Reply-To: <1175979019.28263.523.camel@localhost.localdomain> References: <20070405210316.785839431@mvista.com> <20070407031922.ee49478f.akpm@linux-foundation.org> <1175967839.15973.156.camel@imap.mvista.com> <1175979019.28263.523.camel@localhost.localdomain> Content-Type: text/plain Date: Sat, 07 Apr 2007 14:30:31 -0700 Message-Id: <1175981431.15973.158.camel@imap.mvista.com> Mime-Version: 1.0 X-Mailer: Evolution 2.8.2.1 (2.8.2.1-3.fc6) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2007-04-07 at 22:50 +0200, Thomas Gleixner wrote: > On Sat, 2007-04-07 at 10:43 -0700, Daniel Walker wrote: > > Looks like this path , > > > > arch/i386/kernel/tsc.c: time_cpufreq_notifier(); <-- takes xtime_lock > > mark_tsc_unstable(); > > clocksource_change_rating(&clocksource_tsc, 0); > > timekeeping_change_clocksource(); <-- takes xtime_lock > > > > > > I'm not sure why the time_cpufreq_notifier is taking the xtime_lock tho . > > Simply because it fiddles with variables which are relevant for > timekeeping. loops_per_jiffy perhaps?