From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755850Ab0EKIdt (ORCPT ); Tue, 11 May 2010 04:33:49 -0400 Received: from www.tglx.de ([62.245.132.106]:51871 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753762Ab0EKIdo (ORCPT ); Tue, 11 May 2010 04:33:44 -0400 Date: Tue, 11 May 2010 10:33:35 +0200 (CEST) From: Thomas Gleixner To: Iram Shahzad cc: linux-kernel@vger.kernel.org Subject: Re: hrtimer: about hres_active In-Reply-To: Message-ID: References: <20090206060328.181057235@goodmis.org> <9D38EE7159934A5C85505E9517638040@rainbow> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Iram, please do _NOT_ top post. On Tue, 11 May 2010, Iram Shahzad wrote: > > No. The system switches to high resolution mode late in the boot > > process and it does so only when there is high res capable hardware > > available. > > So far as I checked, hres_active is set to 1 in hrtimer_switch_to_hres. > hrtimer_switch_to_hres is only called from hrtimer_run_pending. > And hrtimer_run_pending is called from timer wheel softirq. > That is why I concluded that hres_active is set at 1st timer softirq. > Do you just mean that it is not the 1st softirq, or do you > mean that in some other place in the late boot process > there is another code which sets hres_active? It happens from softirq context, but not from the 1st softirq. > And is it correct that hres_active remains 1 forever once set to it? Yes. There is no way back. Thanks, tglx