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From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
To: Martin Bligh <mbligh@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	linux-kernel@vger.kernel.org, prasad@linux.vnet.ibm.com,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	od@suse.com, "Frank Ch. Eigler" <fche@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	hch@lst.de, David Wilder <dwilder@us.ibm.com>,
	Tom Zanussi <zanussi@comcast.net>
Subject: Re: [RFC PATCH] LTTng relay buffer allocation, read, write
Date: Tue, 30 Sep 2008 14:14:36 -0400	[thread overview]
Message-ID: <20080930181436.GA19690@Krystal> (raw)
In-Reply-To: <33307c790809301023v1b0755fbsab1bbfa9bfaad58@mail.gmail.com>

* Martin Bligh (mbligh@google.com) wrote:
> On Tue, Sep 30, 2008 at 10:22 AM, Martin Bligh <mbligh@google.com> wrote:
> >> A 4 byte dataless payload is useless anyway.
> >
> > Not at all convinced that's true - we used it for lots of things.
> > Start and end of irq event is one frequent example.
> >
> > Also, in a compact mode, we can record start and end of
> > syscalls like this (without parameters).
> 
> Ah, sorry, maybe I misread this. No data with no event ids, etc
> is fairly useless. 4 bytes data including space to record event ids is OK.

In Steven's scheme, the event IDs in the 4 bytes are reserved for
(useless) internal use ;) They can therefore not be used for specific
tracer event IDs, which I think is a misuse of the precious bits
otherwise available to store really useful event IDs.

Mathieu

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

  reply	other threads:[~2008-09-30 18:14 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-09-27 13:40 [RFC PATCH] LTTng relay buffer allocation, read, write Mathieu Desnoyers
2008-09-27 17:10 ` Peter Zijlstra
2008-09-28  8:59   ` Peter Zijlstra
2008-09-29 16:06     ` Mathieu Desnoyers
2008-09-29 15:50   ` Mathieu Desnoyers
2008-09-29 16:38     ` Steven Rostedt
2008-09-29 18:38       ` Mathieu Desnoyers
2008-09-29 19:40         ` Steven Rostedt
2008-09-29 19:54           ` Steven Rostedt
2008-09-29 17:30     ` Peter Zijlstra
2008-09-29 20:31       ` Mathieu Desnoyers
2008-09-29 21:24         ` Steven Rostedt
2008-09-30 17:22           ` Martin Bligh
2008-09-30 17:23             ` Martin Bligh
2008-09-30 18:14               ` Mathieu Desnoyers [this message]
2008-09-30 18:22                 ` Steven Rostedt
2008-09-30 18:35                   ` Mathieu Desnoyers
2008-09-30 19:43                     ` Steven Rostedt
2008-09-30 20:01                       ` Frank Ch. Eigler
2008-09-30 20:21                         ` Steven Rostedt
2008-09-30 19:44                     ` Martin Bligh
2008-09-30 19:54                       ` Mathieu Desnoyers
2008-09-30 20:49                         ` Martin Bligh
2008-09-30 20:55                           ` Mathieu Desnoyers

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