Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754976Ab0HDP7M (ORCPT ); Wed, 4 Aug 2010 11:59:12 -0400 Received: from e3.ny.us.ibm.com ([32.97.182.143]:42677 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750844Ab0HDP7J (ORCPT ); Wed, 4 Aug 2010 11:59:09 -0400 Subject: Re: [PATCH] [RFC] notify userspace about time changes From: john stultz To: Alexander Shishkin , gregkh@suse.de Cc: lkml@vger.kernel.org, "Kirill A. Shutemov" , Thomas Gleixner , Martin Schwidefsky , Andrew Morton , Jon Hunter , Ingo Molnar , Peter Zijlstra , "Paul E. McKenney" , David Howells , Avi Kivity , "H. Peter Anvin" , John Kacur , linux-kernel@vger.kernel.org In-Reply-To: <1280926108-24668-1-git-send-email-virtuoso@slind.org> References: <1280926108-24668-1-git-send-email-virtuoso@slind.org> Content-Type: text/plain; charset="UTF-8" Date: Wed, 04 Aug 2010 08:58:46 -0700 Message-ID: <1280937526.28884.21.camel@work-vm> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1334 Lines: 31 On Wed, 2010-08-04 at 15:48 +0300, Alexander Shishkin wrote: > Certain userspace applications (like "clock" desktop applets or ntpd) might > want to be notified when some other application changes the system time. It > might also be important for an application to be able to distinguish between > its own and somebody else's time changes. So NTP doesn't actually care, as it will notice the STA_UNSYNC flag is set the next time it checks adjtimex. The clock apps example seems reasonable, but maybe isn't the most compelling argument for adding a new kernel api. Is there a actual use case that you need this for? I don't really have an issue with the code I just really want to make sure the feature would be useful enough to justify the API and code maintenance going forward. Doing some of my own googling, I see Apple added such a notification method, which suggests there are apps that want this. http://stackoverflow.com/questions/690326/how-can-i-get-notified-of-a-system-time-change-in-my-cocoa-application But it doesn't give any specific examples either. thanks -john -- 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/