Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758111AbYFMETd (ORCPT ); Fri, 13 Jun 2008 00:19:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750798AbYFMETZ (ORCPT ); Fri, 13 Jun 2008 00:19:25 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:56466 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750701AbYFMETY (ORCPT ); Fri, 13 Jun 2008 00:19:24 -0400 From: "Takashi Nishiie" To: "'Masami Hiramatsu'" , "'Frank Ch. Eigler'" Cc: "'Peter Zijlstra'" , "'Mathieu Desnoyers'" , "'Hideo AOKI'" , , , "'Steven Rostedt'" References: <20080602232135.GA20173@Krystal> <1212618449.19205.35.camel@lappy.programming.kicks-ass.net> <20080604232241.GA8488@Krystal> <1212653539.19205.47.camel@lappy.programming.kicks-ass.net> <20080612135319.GB22348@Krystal> <1213280823.31518.114.camel@twins> <20080612155332.GA16658@redhat.com> <48514BE3.3000506@redhat.com> <20080612164318.GB17814@redhat.com> <48515770.4020002@redhat.com> <20080612174834.GB22454@redhat.com> <48517A56.20603@redhat.com> In-Reply-To: <48517A56.20603@redhat.com> Subject: RE: Kernel marker has no performance impact on ia64. Date: Fri, 13 Jun 2008 13:19:25 +0900 Message-ID: <004101c8cd0c$aa093190$fe1b94b0$@css.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook 12.0 Content-Language: ja Thread-Index: AcjMxJcOnvU02VETTii74XR3RAzPHQARxPFA Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1965 Lines: 66 Hi,Hiramatsu Hiramatsu wrote: >I think if someone changes the trace point in the kernel, >Module.markers is also changed. > >ex.) > DEFINE_TRACE(sched_switch, (struct task_struct * next, struct task_struct * prev), > next, prev); > >if someone changes above to below, > > DEFINE_TRACE(sched_switch, (int prev_pid, int next_pid), prev_pid, next_pid); > >Module.markers also change like > > sched_switch vmlinux (struct task_struct * next, struct task_struct * prev) > >to > > sched_switch vmlinux (int prev_pid, int next_pid) > >In this case, the below entry never matches to new Module.markers. > >"sched_switch(struct task_struct * next, struct task_struct * prev)":"next %p prev %p" > >Thus, we can find an error. >However, of cause, we should take care of the task_struct changes. The one expected of markers with SystemTap and LTTng is only different the foundation of this discussion. SystemTap: Because the output format is basically defined with user script in systemtap script, "format information" is unnecessary. It can do nothing but guess from "format information" in present markers though the type of the argument is indispensable for SystemTap on the other hand. If the type of an accurate argument is understood, correct processing can be executed. Moreover, being able to refer to the member of the structure if the argument is a pointer of the structure becomes possible, and it is convenient. LTTng: Because the output format is not originally defined in LTTng, "format information" is indispensable. I think that I only have to add the item that shows the type of an accurate argument if the format of "Module.markers" is changed. Thank you, -- Takashi Nishiie -- 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/