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From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
To: "Frank Ch. Eigler" <fche@redhat.com>
Cc: akpm@linux-foundation.org, Christoph Hellwig <hch@infradead.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [patch 0/4] Linux Kernel Markers
Date: Wed, 11 Jul 2007 17:43:20 -0400	[thread overview]
Message-ID: <20070711214320.GA24487@Krystal> (raw)
In-Reply-To: <y0mir8zr4ny.fsf@ton.toronto.redhat.com>

* Frank Ch. Eigler (fche@redhat.com) wrote:
> Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> writes:
> 
> > This updated version of the Linux Kernel Markers mostly adds a unique 16 bits
> > per marker ID and a per-probe marker group. [...]
> 

Hello,

> Could you motivate this part better?  It is not covered in the
> documentation patch.
> 
> It seems to be a way of having a marker handling (callback) module
> give alternate names/ids to markers.  If so, why, considering that
> there is already a private void* callback parameter available to pass
> data back to itself through?
> 

The original reason was to get rid of a supplementary kmalloc() for each
active marker. However, I just noticed that I could pack my private data
in a slab cache, which makes the problem go away. I am therefore
removing IDs and groups from the markers.. they don't really belong to
this low-level infrastructure anyway, so this is all better.

> Also, what if different marker handling modules want to set different
> id/group numbers on the same set of markers?
> 

The way I see things now is to provide the simplest way to do the job,
without over-design. Clearly, putting the IDs and groups there was not
the best idea. I also think it will be up to a "tee" callback module to
implement a list of handlers (notifiers). However, supporting such a
list of handlers should not be a requirement for the low-level markers,
since has a significant performance impact which can be unwanted in the
common case (only one probe connected to a marker).

Mathieu

> - FChE

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

  reply	other threads:[~2007-07-11 21:48 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-07-03 17:08 Mathieu Desnoyers
2007-07-03 17:08 ` [patch 1/4] Linux Kernel Markers, architecture independent code Mathieu Desnoyers
2007-07-03 17:08 ` [patch 2/4] Linux Kernel Markers - Add kconfig menus for the marker code Mathieu Desnoyers
2007-07-03 17:08 ` [patch 3/4] Linux Kernel Markers - Documentation Mathieu Desnoyers
2007-07-03 17:08 ` [patch 4/4] Port of blktrace to the Linux Kernel Markers Mathieu Desnoyers
2007-07-03 18:01 ` [patch 0/4] " Mathieu Desnoyers
2007-07-05  2:00 ` Frank Ch. Eigler
2007-07-11 21:43   ` Mathieu Desnoyers [this message]
  -- strict thread matches above, loose matches on Subject: below --
2007-09-17 18:46 Mathieu Desnoyers
2007-08-27 16:05 Mathieu Desnoyers
2007-08-30 17:12 ` Christoph Hellwig
2007-08-31  1:16   ` Andrew Morton
2007-08-20 20:27 Mathieu Desnoyers
2007-08-12 15:10 Mathieu Desnoyers
2007-07-14  1:29 Mathieu Desnoyers
2006-12-20 23:52 [PATCH " Mathieu Desnoyers
2007-01-13  1:33 ` Richard J Moore
2007-01-13  5:45   ` Mathieu Desnoyers

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