From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH 2/3] perf events: Introduce realtime clock event Date: Sun, 20 Feb 2011 13:49:34 +0100 Message-ID: <20110220124934.GB25700@elte.hu> References: <1298008433-22911-1-git-send-email-daahern@cisco.com> <1298008433-22911-3-git-send-email-daahern@cisco.com> <1298027641.5226.666.camel@laptop> <4D5E84AC.4040104@cisco.com> <1298041106.5226.775.camel@laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx3.mail.elte.hu ([157.181.1.138]:43265 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751447Ab1BTMtr (ORCPT ); Sun, 20 Feb 2011 07:49:47 -0500 Content-Disposition: inline In-Reply-To: <1298041106.5226.775.camel@laptop> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Peter Zijlstra Cc: David Ahern , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, acme@ghostprotocols.net, paulus@samba.org * Peter Zijlstra wrote: > > Programs that generate time-of-day output are using gettimeofday which is tied > > to CLOCK_REALTIME. We want to be able to correlate a perf sample to an entry in > > an applications log file. > > Well, you can argue those programs are broken :-), [...] Then 99% of the world is broken as daylight saving time jumps are part of our lives. > [...] Imagine the joys of trying to figure out wth happens when DST jumps the > clock back an hour and you have an hour of duplicate data. DST means twice a year the clock jumps back and forth by exactly one hour, on a given Saturday night. People debugging logs on Saturday nights and not realizing that there's a (always highly publicized) DST switch going on *deserve* to be surprised twice a year! :-) Really, i dont think it's a big issue - and timestamping in *real* time has very obvious advantages as its name already suggests. Thanks, Ingo