From: Masami Hiramatsu <mhiramat@redhat.com>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Takashi Nishiie <t-nishiie@np.css.fujitsu.com>,
"'Alexey Dobriyan'" <adobriyan@gmail.com>,
"'Peter Zijlstra'" <peterz@infradead.org>,
"'Steven Rostedt'" <rostedt@goodmis.org>,
"'Frank Ch. Eigler'" <fche@redhat.com>,
"'Ingo Molnar'" <mingo@elte.hu>,
"'LKML'" <linux-kernel@vger.kernel.org>,
"'systemtap-ml'" <systemtap@sources.redhat.com>,
"'Hideo AOKI'" <haoki@redhat.com>
Subject: Re: [RFC PATCH] Kernel Tracepoints
Date: Mon, 30 Jun 2008 20:17:00 -0000 [thread overview]
Message-ID: <48693AFB.1020304@redhat.com> (raw)
In-Reply-To: <20080630154002.GE17388@Krystal>
Hi Mathieu,
Mathieu Desnoyers wrote:
> * Masami Hiramatsu (mhiramat@redhat.com) wrote:
>> Mathieu Desnoyers wrote:
>>> * Masami Hiramatsu (mhiramat@redhat.com) wrote:
>>> >
>>>>> Implementation of kernel tracepoints. Inspired from the Linux Kernel Markers.
>>>> What would you think redesigning markers on tracepoints? because most of the
>>>> logic (scaning sections, multiple probe and activation) seems very similar
>>>> to markers.
>>>>
>>> We could, although markers, because they use var args, allow to put the
>>> iteration on the multi probe array out-of-line. Tracepoints cannot
>>> afford this and the iteration must be done at the initial call-site.
>>>
>>> From what I see in your proposal, it's mostly to extract the if() call()
>>> code from the inner __trace_mark() macro and to put it in a separate
>>> macro, am I correct ? This would make the macro more readable.
>> Sure, I think marker and tracepoint can share below functions;
>> - definition of static local variables in specific sections
>
> Given that we could want to keep activation of tracepoints and markers
> separate (so they don't share the same namespace), declaring the static
> variables in separated sections seems to make sense to me.
Sorry, I'm not sure what is "separate activation".
As far as I can see, both tracepoints and markers are activated
when its probe handlers are registered on each tracepoint/marker.
Aren't it separated?
I did not mean integrating registering interfaces, but
I think that they can share base(internal) functions.
for example, both of them has XXX_update_range/_module_XXX_update etc.
IMHO, current code is not so good for maintenance. there are
many code duplications (ex. kernel/module.c, I think
that both of them (and imv too?) can share the code for
handling its section and iterating entries). I'm not sure those
duplications are acceptable.
>> - probe activation code (if() call())
>> - multi probe handling
>
> Hrm, the thing here is that because markers allow to do the iteration on
> the multiple probe callbacks within an internal wrapper (instead of
> doing it on-site as in the tracepoints), it allows to do some further
> optimizations (less memory allocation and less pointer dereference in
> the single probe case, not having to prepare the va_args in the
> MARK_NOARGS case) which are only done because it does not have to add
> code to the instrumentation site. However, tracepoints cannot have such
> "generic" wrapper and we have to do the iteration on callbacks in the
> code added to the instrumented object. Therefore, I keep it as small as
> possible in terms of bytes of instructions.
OK, I see. So, __tracepoint_block() macro can specify handler function.
what would you think about it?
Thank you,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com
next prev parent reply other threads:[~2008-06-30 20:00 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-20 19:36 [RFC][Patch 2/2] markers: example of irq regular kernel markers Masami Hiramatsu
2008-06-20 22:16 ` Mathieu Desnoyers
2008-06-20 23:23 ` Masami Hiramatsu
2008-06-21 15:08 ` KOSAKI Motohiro
2008-06-21 18:04 ` Steven Rostedt
2008-06-21 19:41 ` Frank Ch. Eigler
2008-06-22 4:03 ` Steven Rostedt
2008-06-22 4:32 ` Peter Zijlstra
2008-06-22 17:12 ` Frank Ch. Eigler
2008-06-23 2:20 ` Masami Hiramatsu
2008-06-23 7:08 ` KOSAKI Motohiro
2008-06-22 18:03 ` Frank Ch. Eigler
2008-06-22 18:27 ` Masami Hiramatsu
2008-06-21 10:14 ` Peter Zijlstra
2008-06-23 3:06 ` [RFC] Tracepoint proposal Mathieu Desnoyers
2008-06-23 6:34 ` Alexey Dobriyan
2008-06-23 6:51 ` Mathieu Desnoyers
2008-06-24 7:15 ` Alexey Dobriyan
2008-06-24 11:39 ` Masami Hiramatsu
2008-06-24 13:23 ` Takashi Nishiie
2008-06-24 16:23 ` Frank Ch. Eigler
2008-06-24 19:43 ` Masami Hiramatsu
2008-06-25 1:08 ` KOSAKI Motohiro
2008-06-25 1:36 ` Masami Hiramatsu
2008-06-25 1:49 ` Mathieu Desnoyers
2008-06-26 16:20 ` [RFC PATCH] Tracepoint sched probes Mathieu Desnoyers
2008-06-26 17:01 ` [RFC PATCH] Kernel Tracepoints Mathieu Desnoyers
2008-06-27 13:21 ` Masami Hiramatsu
2008-06-27 15:00 ` Mathieu Desnoyers
2008-06-29 18:46 ` Masami Hiramatsu
2008-06-30 18:21 ` Mathieu Desnoyers
2008-06-27 15:07 ` Mathieu Desnoyers
2008-06-30 20:11 ` Masami Hiramatsu
2008-06-27 15:48 ` Mathieu Desnoyers
2008-06-28 0:05 ` Masami Hiramatsu
2008-06-30 17:14 ` Mathieu Desnoyers
2008-06-30 20:17 ` Masami Hiramatsu [this message]
2008-07-03 15:13 ` Mathieu Desnoyers
2008-07-03 18:53 ` Masami Hiramatsu
2008-06-27 16:11 ` [RFC PATCH] Kernel Tracepoints (update) Mathieu Desnoyers
2008-07-03 15:29 ` Masami Hiramatsu
2008-07-03 15:47 ` Mathieu Desnoyers
2008-07-03 18:19 ` Mathieu Desnoyers
2008-07-03 18:48 ` Masami Hiramatsu
2008-06-24 11:06 ` [RFC] Tracepoint proposal Masami Hiramatsu
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