From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "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>
Subject: Re: [for-next][PATCH 08/20] tracing: Warn if a tracepoint is not set via debugfs
Date: Thu, 13 Mar 2014 03:10:53 +0000 (UTC) [thread overview]
Message-ID: <209084517.2310.1394680253793.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <20140312204907.6b8d402c@gandalf.local.home>
----- Original Message -----
> From: "Steven Rostedt" <rostedt@goodmis.org>
> To: "Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>
> Cc: "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 8:49:07 PM
> Subject: Re: [for-next][PATCH 08/20] tracing: Warn if a tracepoint is not set via debugfs
>
> On Wed, 12 Mar 2014 19:51:01 +0000 (UTC)
> Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
>
> > This only leaves tracepoints in header files and the impact of LTO as
> > requirements for having tracepoint callsites with the same name across
> > modules.
>
> The only thing that needs to be unique is the struct tracepoint
> __tracepoint_##name. There should not be any duplicates of those. I
> can't see how the LTO would duplicate a data structure without screwing
> everything (not just tracepoints) up.
>
> We can still have more than one trace_##name() called, as that is
> handled by the static key.
Hrm, I seem to have mixed up the concerns regarding compiler
optimisations between the static keys with those related to tracepoints
(including that their predecessors "kernel markers" worked more like
static keys than tracepoint). I did work in both area pretty much at the
same time back in 2007-2008.
Having gotten my head back up straight, I now see the point in your
proposal. Thanks for bearing with me.
Even if we ever want to have tracepoints within header files, as long
as we have the DECLARE_TRACE() within the header, and a DEFINE_TRACE()
in one location in the loaded kernel image (or a loaded module we depend
on), it should be possible too. All tracepoint.c cares about is the site
defined by DEFINE_TRACE().
>
> Note, I'm scrambling to get ready for my trip tomorrow. Thus, I'm not
> as much at the computer. I may work on some patches in my 6 hour
> layover though.
Allright. Have a good trip!
Thanks,
Mathieu
>
> -- Steve
>
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2014-03-13 3:10 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
2014-03-13 0:49 ` Steven Rostedt
2014-03-13 3:10 ` Mathieu Desnoyers [this message]
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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