From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756218Ab0KRMGa (ORCPT ); Thu, 18 Nov 2010 07:06:30 -0500 Received: from mail.openrapids.net ([64.15.138.104]:39980 "EHLO blackscsi.openrapids.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750917Ab0KRMG3 (ORCPT ); Thu, 18 Nov 2010 07:06:29 -0500 Date: Thu, 18 Nov 2010 07:06:26 -0500 From: Mathieu Desnoyers To: Steven Rostedt Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Thomas Gleixner , Frederic Weisbecker , Darren Hart , Linus Torvalds , "jason.wessel" , "Ted Ts'o" Subject: Re: [RFC][PATCH 0/2] tracing: Have trace_printk()s in the events/ directory Message-ID: <20101118120626.GB27474@Krystal> References: <20101118035803.453609353@goodmis.org> <1290076866.2109.1305.camel@laptop> <1290081203.30543.96.camel@gandalf.stny.rr.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1290081203.30543.96.camel@gandalf.stny.rr.com> X-Editor: vi X-Info: http://www.efficios.com X-Operating-System: Linux/2.6.26-2-686 (i686) X-Uptime: 07:01:55 up 56 days, 16:04, 1 user, load average: 1.21, 1.27, 1.18 User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Steven Rostedt (rostedt@goodmis.org) wrote: > On Thu, 2010-11-18 at 11:41 +0100, Peter Zijlstra wrote: > > On Wed, 2010-11-17 at 22:58 -0500, Steven Rostedt wrote: > > > For example, I added a trace_printk() in kernel/sched.c at line 2180 > > > and it creates: > > > > > > # ls /debug/tracing/events/printk/kernel/sched.c/2180/ > > > enable format > > > > > > The format is the printk format: > > > > > > # cat /debug/tracing/events/printk/kernel/sched.c/2180/format > > > "migrate task %s:%d" > > > > *groan*, so you're creating a tracepoint per instance? > > > > That's going to be massive pain for perf.. I really don't see the point > > in splitting all that out. > > a) The file directory was what was asked about in the referenced email. > b) This is just an example of a way to display it to the user, which > seems to be very intuitive. > c) Perf can implement the details anyway it wants. It can make a single > tracepoint callback and have the enabling of the points as a special > filter. > d) This was just an RFC that Frederic asked if I would do. I thought it > would be a fun challenge and did it. Let it bit rot in hell for all I > care, I wasn't taking it any further anyway. Hi Steven, The LTTng tree still keeps the "trace_mark()" kernel markers, which are very very similar to ftrace_printk(). I'd be happy to combine the two eventually. This one file per line approach seems very good -- rather than explicitely naming each instance, as I did in trace_mark(), you end up automatically naming them by file/line number. How does this behave from within static inlines called multiple times and unrolled loops ? Thanks, Mathieu -- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com