From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751785AbWBMOOe (ORCPT ); Mon, 13 Feb 2006 09:14:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751787AbWBMOOe (ORCPT ); Mon, 13 Feb 2006 09:14:34 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:12721 "EHLO mx3.mail.elte.hu") by vger.kernel.org with ESMTP id S1751785AbWBMOOd (ORCPT ); Mon, 13 Feb 2006 09:14:33 -0500 Date: Mon, 13 Feb 2006 15:12:50 +0100 From: Ingo Molnar To: Roman Zippel Cc: Andrew Morton , tglx@linutronix.de, linux-kernel@vger.kernel.org Subject: Re: [PATCH 12/13] hrtimer: optimize hrtimer_get_remaining Message-ID: <20060213141250.GH12923@elte.hu> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=AWL autolearn=no SpamAssassin version=3.0.3 0.0 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Roman Zippel wrote: > hrtimer_get_remaining doesn't need to lock the hrtimer_base to read > the time. Also use hrtimer_get_remaining at two other places. nack - it's not only about ->get_time() atomicity: > - base = lock_hrtimer_base(timer, &flags); > - rem = ktime_sub(timer->expires, timer->base->get_time()); > - unlock_hrtimer_base(timer, &flags); timer->expires is a 64-bit value, which might be read nonatomically on 32-bit platforms. Wherever it's safe, we already open-code this ktime_sub() - if you find more places then please do it that way. definitely not something for v2.6.16. Ingo