Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756683Ab1EKP7G (ORCPT ); Wed, 11 May 2011 11:59:06 -0400 Received: from casper.infradead.org ([85.118.1.10]:54151 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756606Ab1EKP7A (ORCPT ); Wed, 11 May 2011 11:59:00 -0400 Subject: Re: [tip:timers/core] timerfd: Allow timers to be cancelled when clock was set From: Peter Zijlstra To: Kay Sievers Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com, johnstul@us.ibm.com, davidel@xmailserver.org, virtuoso@slind.org, tglx@linutronix.de, chris.friesen@genband.com, kirill@shutemov.name, linux-tip-commits@vger.kernel.org In-Reply-To: References: <1305109433.2914.208.camel@laptop> Content-Type: text/plain; charset="UTF-8" Date: Wed, 11 May 2011 15:45:41 +0200 Message-ID: <1305121541.2914.213.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1658 Lines: 35 On Wed, 2011-05-11 at 13:58 +0200, Kay Sievers wrote: > On Wed, May 11, 2011 at 12:23, Peter Zijlstra wrote: > > On Mon, 2011-05-02 at 19:44 +0000, tip-bot for Thomas Gleixner wrote: > >> Commit-ID: 99ee5315dac6211e972fa3f23bcc9a0343ff58c4 > >> Gitweb: http://git.kernel.org/tip/99ee5315dac6211e972fa3f23bcc9a0343ff58c4 > >> Author: Thomas Gleixner > >> AuthorDate: Wed, 27 Apr 2011 14:16:42 +0200 > >> Committer: Thomas Gleixner > >> CommitDate: Mon, 2 May 2011 21:39:15 +0200 > >> > >> timerfd: Allow timers to be cancelled when clock was set > >> > >> Some applications must be aware of clock realtime being set > >> backward. A simple example is a clock applet which arms a timer for > >> the next minute display. If clock realtime is set backward then the > >> applet displays a stale time for the amount of time which the clock > >> was set backwards. Due to that applications poll the time because we > >> don't have an interface. > > > > Shouldn't that clock applet use CLOCK_MONOTONIC for the timer anyway? > > Like: Hey let's meet at the bar 5 hours after bootup? :) Uhm, the example was a timer to update the displayed time, so a timer like: wake me next minute, suffices. The whole what to do with appointments when switching timezones wasn't mentioned, but that too should be able to be sorted with a clkadjust notifier. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/