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From: "Martin Bligh" <mbligh@google.com>
To: "Mathieu Desnoyers" <mathieu.desnoyers@polymtl.ca>
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 13:49:48 -0700	[thread overview]
Message-ID: <33307c790809301349g6f702ffq356c37e24cdfaa63@mail.gmail.com> (raw)
In-Reply-To: <20080930195409.GA24169@Krystal>

> I am not saying anything about the actual number of events with 0 bytes
> payload I actually have in my own instrumentation, if this is what you
> mean. I am just saying that it leaves this room available for such
> events.

It would, yes. Are they useful?

> Even if there is a 32 bits payload associated with those events, the
> fact that we can encode the event ID in the 32 bits header will bring
> those events from 96 bits (due to 32 bits alignment) down to 64 bits.

That's true. So do we have a bunch of stuff that we really really need
that'd fit into 32 bits, but not 28 bits?

>> This is all over 1 bit of information, right? Since you need at least 1 for
>> the timestamp stuff.
>
> 4 bits of information could be added to the 32-bits header if we allow
> tracers to register their first 15 event IDs in those 4 bits.
>
> But well... let's keep that for v2. ;)

Sounds like a plan ;-) All this stuff is internal representations anyway.

  reply	other threads:[~2008-09-30 20:50 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-09-27 13:40 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
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 [this message]
2008-09-30 20:55                           ` Mathieu Desnoyers

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