linux-kernel - Re: [PATCH 3/5] trace: Add per

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Message-ID: <CAL26m8Jb-PO7z0+gcwhkxB0q36pA7Fe9Tz=Pimq8kua8yahvgA@mail.gmail.com>
Date:	Fri, 29 Jul 2011 12:13:53 -0700
From:	Vaibhav Nagarnaik <vnagarnaik@...gle.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	Michael Rubin <mrubin@...gle.com>,
	David Sharp <dhsharp@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] trace: Add per_cpu ring buffer control files

On Fri, Jul 29, 2011 at 11:14 AM, Steven Rostedt <rostedt@...dmis.org> wrote:
> On Tue, 2011-07-26 at 15:59 -0700, Vaibhav Nagarnaik wrote:
>> Add a debugfs entry under per_cpu/ folder for each cpu called
>> buffer_size_kb to control the ring buffer size for each CPU
>> independently.
>>
>> If the global file buffer_size_kb is used to set size, the individual
>> ring buffers will be adjusted to the given size. The buffer_size_kb will
>> report the common size to maintain backward compatibility.
>>
>> If the buffer_size_kb file under the per_cpu/ directory is used to
>> change buffer size for a specific CPU, only the size of the respective
>> ring buffer is updated. When tracing/buffer_size_kb is read, it reports
>> the ring buffer sizes of all the CPUs at that point.
>
> No, buffer_size_kb should not change in the what it reports. This is why
> you have a buffer_total_size_kb. Use that. If the per_cpu buffers are
> changed, then this should just report "various" or something to that
> affect. This will be a good way to know if the per_cpu buffers are the
> same or not.

Aargh.

I updated the code to return 'X' when individual cpu buffers don't match
up in size and forgot to update the changelog, I will do it now.


Vaibhav Nagarnaik
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