Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965157AbWIQXgP (ORCPT ); Sun, 17 Sep 2006 19:36:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965158AbWIQXgP (ORCPT ); Sun, 17 Sep 2006 19:36:15 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:59858 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S965157AbWIQXgO (ORCPT ); Sun, 17 Sep 2006 19:36:14 -0400 Date: Mon, 18 Sep 2006 01:27:14 +0200 From: Ingo Molnar To: Roman Zippel Cc: Paul Mundt , Karim Yaghmour , linux-kernel , Ingo Molnar , Jes Sorensen , Andrew Morton , Tom Zanussi , Richard J Moore , "Frank Ch. Eigler" , Michel Dagenais , Mathieu Desnoyers , Christoph Hellwig , Greg Kroah-Hartman , Thomas Gleixner , William Cohen , "Martin J. Bligh" Subject: Re: tracepoint maintainance models Message-ID: <20060917232714.GA18713@elte.hu> References: <450D182B.9060300@opersys.com> <20060917112128.GA3170@localhost.usen.ad.jp> <20060917143623.GB15534@elte.hu> <20060917150953.GB20225@elte.hu> 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: -3.7 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-3.7 required=5.9 tests=ALL_TRUSTED,AWL,BAYES_40 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts -1.1 BAYES_40 BODY: Bayesian spam probability is 20 to 40% [score: 0.3442] 0.7 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 Content-Length: 1767 Lines: 41 * Roman Zippel wrote: > What is so special between users of dynamic and static tracers, that > the former will never complain, if some tracepoint doesn't work > anymore? If by breakage you mean accidental regressions, i was not talking about accidental breakages when i suggested that dynamic tracers would not see them. The "breakage" i talked about, and which would cause regressions to static tracer users but would not be noticed by dynamic tracer users was: _the moving of a static marker to a dynamic script_ (see <20060915204812.GA6909@elte.hu>, my first paragraph there. Also see <20060917143623.GB15534@elte.hu> for the same topic.) this breaks static tracers, but dynamic tracers remain unaffected, because the dynamic probe (or the function attribute) still offers equivalent functionality. Hence users of dynamic tracers still have the same functionality - while users of static tracers see breakage. Ok? If you meant accidental breakages, then of course users of both types of tracers would be affected, but even in this case there's a more subtle difference here, which i explained in <20060917143623.GB15534@elte.hu>: >> In fact, with dynamic tracers, an end-user visible breakage can even >> be fixed _after the main kernel has been released, compiled and >> booted on the end-user's system_. Systemtap scripts can be updated on >> live systems. So there is very, very little maintainance pressure >> caused by dynamic tracing. i hope this explains. Ingo - 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/