From: Masami Hiramatsu <mhiramat@redhat.com>
To: Martin Bligh <mbligh@google.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Mathieu Desnoyers <compudj@krystal.dyndns.org>,
Steven Rostedt <rostedt@goodmis.org>,
od@novell.com, "Frank Ch. Eigler" <fche@redhat.com>,
systemtap-ml <systemtap@sources.redhat.com>
Subject: Re: Unified tracing buffer
Date: Mon, 22 Sep 2008 19:47:00 -0000 [thread overview]
Message-ID: <48D7F5E8.3000705@redhat.com> (raw)
In-Reply-To: <33307c790809191433w246c0283l55a57c196664ce77@mail.gmail.com>
Hi Martin,
Martin Bligh wrote:
> During kernel summit and Plumbers conference, Linus and others
> expressed a desire for a unified
> tracing buffer system for multiple tracing applications (eg ftrace,
> lttng, systemtap, blktrace, etc) to use.
> This provides several advantages, including the ability to interleave
> data from multiple sources,
> not having to learn 200 different tools, duplicated code/effort, etc.
>
> Several of us got together last night and tried to cut this down to
> the simplest usable system
> we could agree on (and nobody got hurt!). This will form version 1.
> I've sketched out a few
> enhancements we know that we want, but have agreed to leave these
> until version 2.
> The answer to most questions about the below is "yes we know, we'll
> fix that in version 2"
> (or 3). Simplicity was the rule ...
>
> Sketch of design. Enjoy flaming me. Code will follow shortly.
>
>
> STORAGE
> -------
>
> We will support multiple buffers for different tracing systems, with
> separate names, event id spaces.
> Event ids are 16 bit, dynamically allocated.
> A "one line of text" print function will be provided for each event,
> or use the default (probably hex printf)
> Will provide a "flight data recorder" mode, and a "spool to disk" mode.
>
> Circular buffer per cpu, protected by per-cpu spinlock_irq
> Word aligned records.
> Variable record length, header will start with length record.
> Timestamps in fixed timebase, monotonically increasing (across all CPUs)
I agree to integrate tracing buffer mechanism, but I don't think
your proposal is the simplest one.
To simplify, I think the layered buffering mechanism is desirable.
- The lowest layer just provides named circular buffers(both per-cpu and
uni-buffer in system) and read/write scheme.
- Next layer provides user/kernel interface including controls.
- Top layer defines packet(and event) formatting utilities.
- Additionally, it would better provide some library routines(timestamp,
event-id synchronize, and so on).
Since this unified buffer is used from different kind of tracers/loggers,
I don't think all of them(and future tracers) want to be tied down by
"event-id"+"parameter" format.
So, Sorry, I disagree about that the tracing buffer defines its *data format*,
it's just overkill for me.
Thank you,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com
next parent reply other threads:[~2008-09-22 19:47 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <33307c790809191433w246c0283l55a57c196664ce77@mail.gmail.com>
2008-09-22 19:47 ` Masami Hiramatsu [this message]
2008-09-22 20:14 ` Martin Bligh
2008-09-22 22:27 ` Masami Hiramatsu
2008-09-22 23:12 ` Darren Hart
2008-09-23 0:06 ` Masami Hiramatsu
2008-09-22 23:17 ` Martin Bligh
2008-09-23 0:07 ` Masami Hiramatsu
2008-09-23 0:13 ` Martin Bligh
2008-09-23 14:51 ` Masami Hiramatsu
2008-09-23 15:09 ` Mathieu Desnoyers
2008-09-23 15:32 ` Masami Hiramatsu
2008-09-23 16:02 ` Linus Torvalds
2008-09-23 17:07 ` Masami Hiramatsu
2008-09-23 17:33 ` Thomas Gleixner
2008-09-23 19:03 ` Masami Hiramatsu
2008-09-23 19:37 ` Thomas Gleixner
2008-09-23 19:39 ` Martin Bligh
2008-09-23 19:42 ` Thomas Gleixner
2008-09-23 19:51 ` Martin Bligh
2008-09-23 20:05 ` Thomas Gleixner
2008-09-23 21:02 ` Martin Bligh
2008-09-23 20:06 ` Masami Hiramatsu
2008-09-23 20:09 ` Thomas Gleixner
2008-09-23 15:48 ` Linus Torvalds
2008-09-23 0:41 ` Linus Torvalds
2008-09-23 1:28 ` Roland Dreier
2008-09-23 1:40 ` Steven Rostedt
2008-09-23 2:08 ` Mathieu Desnoyers
2008-09-23 2:27 ` Darren Hart
2008-09-23 2:32 ` Mathieu Desnoyers
2008-09-23 3:29 ` Linus Torvalds
2008-09-23 3:42 ` Mathieu Desnoyers
2008-09-23 4:06 ` Linus Torvalds
2008-09-23 3:44 ` Steven Rostedt
2008-09-23 4:12 ` Masami Hiramatsu
2008-09-23 4:18 ` Martin Bligh
2008-09-23 15:25 ` Masami Hiramatsu
2008-09-23 10:54 ` Steven Rostedt
2008-09-23 4:20 ` Linus Torvalds
2008-09-23 14:13 ` Mathieu Desnoyers
2008-09-23 2:31 ` Mathieu Desnoyers
2008-09-23 3:07 ` Masami Hiramatsu
2008-09-23 14:38 ` KOSAKI Motohiro
2008-09-23 15:04 ` Frank Ch. Eigler
2008-09-23 15:23 ` Masami Hiramatsu
2008-09-23 18:04 ` KOSAKI Motohiro
2008-09-23 18:29 ` Martin Bligh
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