From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751798AbZHXG4M (ORCPT ); Mon, 24 Aug 2009 02:56:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751619AbZHXG4M (ORCPT ); Mon, 24 Aug 2009 02:56:12 -0400 Received: from casper.infradead.org ([85.118.1.10]:37609 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751574AbZHXG4L (ORCPT ); Mon, 24 Aug 2009 02:56:11 -0400 Subject: Re: system gets stuck in a lock during boot From: Peter Zijlstra To: Li Zefan Cc: "Justin P. Mattock" , Steven Rostedt , Frederic Weisbecker , Linux Kernel Mailing List , Ingo Molnar In-Reply-To: <4A922F82.9080000@cn.fujitsu.com> References: <4A84345D.60506@gmail.com> <20090818104905.GC5231@nowhere> <20090818160911.GA21243@goodmis.org> <4A8B4607.6090303@gmail.com> <4A8B5113.20102@cn.fujitsu.com> <4A8FA2BD.4030707@gmail.com> <4A91FDED.9050801@cn.fujitsu.com> <1251093523.7538.118.camel@twins> <4A922F82.9080000@cn.fujitsu.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Mon, 24 Aug 2009 08:55:25 +0200 Message-Id: <1251096925.7538.121.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2009-08-24 at 14:13 +0800, Li Zefan wrote: > Peter Zijlstra wrote: > > On Mon, 2009-08-24 at 10:41 +0800, Li Zefan wrote: > > > >>> @@ -940,7 +940,7 @@ event_create_dir(struct ftrace_event_call *call, struct dentr > >>> entry = trace_create_file("enable", 0644, call->dir, call, > >>> enable); > >>> > >>> - if (call->id) > >>> + if (call->id && call->profile_enable) > >> We do an extra check on ->profile_enable, shouldn't cause bug.. > >> > >>> entry = trace_create_file("id", 0444, call->dir, call, > >>> id); > >> Any way, I don't think this commit does the right thing: > >> > >> - If CONFIG_EVENT_PROFILE=y, we'll create events///id, > >> except events/ftrace//id. > >> > >> - if CONFIG_EVENT_PROFILE=n, there's no 'id' file at all! > >> > >> I think it's better to skip ftrace/ dir in perf tool code, instead of > >> skipping creating id files in ftrace code. > > > > No, it does do the right thing. Your patch breaks things because not all > > tracepoints are created through TRACE_EVENT() and will thus not have > > their profile_enable/disable hooks set. > > > > By giving them an ID file, there is no way to distinguish good from bad > > tracepoints. > > > > But removing the id file from events/ftrace/ might break some ftrace > binary parsers? > > And this commit makes 'id' file disapeared with CONFIG_EVENT_PROFILE=n. I introduced the id file for EVENT_PROFILE, tough luck if someone else relies on it. > > Expempting ftrace is no solid solution, suppose someone else does a > > TRACE_EVENT_FORMAT() tracepoint, how would you know you could use it as > > a profile event source? > > > > Agree. > > > The id files really must stay conditional. > > > > I don't think it's a good idea to connect it with perfcounter > this way. Wouldn't adding a 'profilable' file more intuitive? its called: id ;-)