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Message-ID: <alpine.DEB.2.00.0907202124490.11494@gandalf.stny.rr.com>
Date: Mon, 20 Jul 2009 21:25:10 -0400 (EDT)
From: Steven Rostedt <rostedt@...dmis.org>
To: Li Zefan <lizf@...fujitsu.com>
cc: Johannes Berg <johannes@...solutions.net>,
linux-kernel <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...e.hu>,
Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: event tracing, ringbuffer and RB_MAX_SMALL_DATA
On Thu, 16 Jul 2009, Li Zefan wrote:
> Johannes Berg wrote:
> > On Wed, 2009-07-15 at 09:08 +0800, Li Zefan wrote:
> >
> >> Right, the length of a dynamic array is not recorded, and this
> >> causes 2 problems:
> >>
> >> - the event filter is not working properly for dynamic strings
> >> - userspace parsers can't figure out the length of those arrays
> >>
> >> I had an idea some time ago, and hopefully will send out a
> >> patch today or tomorrow.
> >
> > Well except for the corner case I pointed out, you can determine the
> > length of dynamic arrays by either
> > - the next dynamic array's offset or
> > - the length of the item.
> >
> > So, afaict, the simplest solution would be to not embed the length of
> > the item in type_len if it's not divisible by four and contains dynamic
> > members, though the latter condition might be hard to check.
> >
>
> Actually I'm going to encode the size of a dynamic array
> in it's @offset, so the lower 16bits is offset and the
> higher 16bits is size.
Was there a patch sent out to do this yet, or is this still something
being worked on?
Thanks,
-- Steve
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