From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
"Frank Ch. Eigler" <fche@redhat.com>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Johannes Berg <johannes.berg@intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
lttng-dev <lttng-dev@lists.lttng.org>,
Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [for-next][PATCH 08/20] tracing: Warn if a tracepoint is not set via debugfs
Date: Thu, 13 Mar 2014 03:21:27 +0000 (UTC) [thread overview]
Message-ID: <2020214533.2317.1394680887617.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <20140313031501.GW22728@two.firstfloor.org>
----- Original Message -----
> From: "Andi Kleen" <andi@firstfloor.org>
> To: "Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>
> Cc: "Andi Kleen" <andi@firstfloor.org>, "Steven Rostedt" <rostedt@goodmis.org>, "Frank Ch. Eigler" <fche@redhat.com>,
> linux-kernel@vger.kernel.org, "Ingo Molnar" <mingo@kernel.org>, "Frederic Weisbecker" <fweisbec@gmail.com>, "Andrew
> Morton" <akpm@linux-foundation.org>, "Johannes Berg" <johannes.berg@intel.com>, "Linus Torvalds"
> <torvalds@linux-foundation.org>, "Peter Zijlstra" <peterz@infradead.org>, "Thomas Gleixner" <tglx@linutronix.de>,
> "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>, "lttng-dev" <lttng-dev@lists.lttng.org>, "Rusty Russell"
> <rusty@rustcorp.com.au>
> Sent: Wednesday, March 12, 2014 11:15:01 PM
> Subject: Re: [for-next][PATCH 08/20] tracing: Warn if a tracepoint is not set via debugfs
>
> On Wed, Mar 12, 2014 at 08:47:07PM +0000, Mathieu Desnoyers wrote:
> > ----- Original Message -----
> > > From: "Andi Kleen" <andi@firstfloor.org>
> > > To: "Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>
> > > Cc: "Steven Rostedt" <rostedt@goodmis.org>, "Frank Ch. Eigler"
> > > <fche@redhat.com>, linux-kernel@vger.kernel.org, "Ingo
> > > Molnar" <mingo@kernel.org>, "Frederic Weisbecker" <fweisbec@gmail.com>,
> > > "Andrew Morton" <akpm@linux-foundation.org>,
> > > "Johannes Berg" <johannes.berg@intel.com>, "Linus Torvalds"
> > > <torvalds@linux-foundation.org>, "Peter Zijlstra"
> > > <peterz@infradead.org>, "Thomas Gleixner" <tglx@linutronix.de>, "Greg
> > > Kroah-Hartman" <gregkh@linuxfoundation.org>,
> > > "lttng-dev" <lttng-dev@lists.lttng.org>, "Rusty Russell"
> > > <rusty@rustcorp.com.au>, "Andi Kleen" <andi@firstfloor.org>
> > > Sent: Wednesday, March 12, 2014 4:35:15 PM
> > > Subject: Re: [for-next][PATCH 08/20] tracing: Warn if a tracepoint is not
> > > set via debugfs
> > >
> > > > So I understand that you wish to banish tracepoints from static inline
> > > > functions within headers to ensure they only appear within a single
> > > > module.
> > > > This seems to be a step backward, but let's assume we stick to that
> > > > rule.
> > > > Then how do you envision dealing with Link-Time Optimisations (LTO) ?
> > >
> > > I assume it uses the file name defines set by Kbuild?
> >
> > Just to make sure I understand your question: I understand that you are
> > asking
> > whether tracepoints use file name defines at all in the naming of a
> > tracepoint.
> > The answer to this question is: No, they do not.
>
> Ok. It uses kallsyms? That can change of course.
As I just replied to Steven, I now see that I mixed up concerns about
static keys, and the prior kernel markers, with tracepoint concerns.
The way they are implemented are very much different (Hey! I should know,
I wrote that code some 6 years ago!) ;)
> >
> > > These don't change with
> > > LTO. It's whatever was specified at compile time. Also LTO doesn't
> > > inline over module boundaries (if the module is not built in)
> >
> > Good to know. Can it inline core kernel functions into a module ?
>
> Each module and the main kernel are currently LTO'ed separately.
>
> In theory it would be possible to change this, but likely at some
> compile time cost.
OK, thanks for the explanations!
Mathieu
>
> -Andi
>
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2014-03-13 3:21 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-07 15:09 [for-next][PATCH 00/20] tracing: linux-next updates Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 01/20] ftrace/x86: Run a sync after fixup on failure Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 02/20] ftrace/x86: One more missing sync after fixup of function modification failure Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 03/20] tracepoint: Do not waste memory on mods with no tracepoints Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 04/20] ftrace/x86: Have ftrace_write() return -EPERM and clean up callers Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 05/20] tracing: Move raw output code from macro to standalone function Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 06/20] tracing: Move event storage for array " Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 07/20] tracing: Use helper functions in event assignment to shrink macro size Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 08/20] tracing: Warn if a tracepoint is not set via debugfs Steven Rostedt
2014-03-10 20:01 ` Mathieu Desnoyers
2014-03-10 20:19 ` Steven Rostedt
2014-03-10 20:55 ` Mathieu Desnoyers
2014-03-11 2:41 ` Frank Ch. Eigler
2014-03-11 2:58 ` Steven Rostedt
2014-03-11 4:08 ` Mathieu Desnoyers
2014-03-11 14:46 ` Steven Rostedt
2014-03-11 14:26 ` Frank Ch. Eigler
2014-03-11 15:06 ` Mathieu Desnoyers
2014-03-11 15:40 ` Steven Rostedt
2014-03-11 17:34 ` Mathieu Desnoyers
2014-03-11 19:13 ` Steven Rostedt
2014-03-12 14:24 ` Mathieu Desnoyers
2014-03-12 15:11 ` Steven Rostedt
2014-03-12 15:46 ` Steven Rostedt
2014-03-12 16:05 ` Mathieu Desnoyers
2014-03-12 16:18 ` Steven Rostedt
2014-03-12 16:39 ` Mathieu Desnoyers
2014-03-12 17:50 ` Steven Rostedt
2014-03-12 18:47 ` Mathieu Desnoyers
2014-03-12 18:58 ` Steven Rostedt
2014-03-12 19:30 ` Steven Rostedt
2014-03-12 19:58 ` Mathieu Desnoyers
2014-03-12 19:51 ` Mathieu Desnoyers
2014-03-12 20:35 ` Andi Kleen
2014-03-12 20:47 ` Mathieu Desnoyers
2014-03-13 3:15 ` Andi Kleen
2014-03-13 3:21 ` Mathieu Desnoyers [this message]
2014-03-13 0:49 ` Steven Rostedt
2014-03-13 3:10 ` Mathieu Desnoyers
2014-03-13 15:24 ` Mathieu Desnoyers
2014-03-12 16:40 ` Mathieu Desnoyers
2014-03-12 18:02 ` Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 09/20] tracing: Fix event header writeback.h to include tracepoint.h Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 10/20] tracing: Fix event header migrate.h " Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 11/20] tracing/module: Replace include of tracepoint.h with jump_label.h in module.h Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 12/20] tracing: Correctly expand len expressions from __dynamic_array macro Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 13/20] tracing: Evaluate len expression only once in " Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 14/20] ftrace: Cleanup of global variables ftrace_new_pgs and ftrace_update_cnt Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 15/20] ftrace: Inline the code from ftrace_dyn_table_alloc() Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 16/20] ftrace: Pass retval through return in ftrace_dyn_arch_init() Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 17/20] ftrace: Do not pass data to ftrace_dyn_arch_init Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 18/20] ftrace: Remove freelist from struct dyn_ftrace Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 19/20] ftrace: Warn on error when modifying ftrace function Steven Rostedt
2014-03-07 15:09 ` [for-next][PATCH 20/20] ftrace/x86: BUG when ftrace recovery fails Steven Rostedt
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